Madness called Postgraduate Medical Entrance Exams!

I was just going through the drafts in my blog, and to my pleasant surprise, came across the following one, which was basically meant to be soft copy of my notes to be read on a cell phone. That was year 2008-09. So, publishing this vomitus for the old times’ sake. 🙂 [Yeah, you shouldn’t get rudely shocked to find a doctor get pleasantly surprised to rediscover old vomitus].

> FMT
* Toxicology
# Arsenic poisoning
– “Mn” Ma Me Na Ne Ra Re Fa Fe Pu Pe
– Ma-Marsh test
– Me-Mee’s line on nails
– Na-nausea
– Ne-neuritis/numbness
– Ra-Raindrop appearance of skin (hyperkeratosis of palms and soles)
– Re-Reinsch test
– Fa-fatal dose—120-200 mg
– Fe-ferric chloride hydrate precipitate-Rx
– Pu-putrefaction delayed (possibly by opposing bacterial growth)
– Pe-Petechial hemorrhages under the left endocardium
– “M” Arsenic trioxide is the most poisonous salt

# Lead poisoning
– “Mn” New ABCDEF
– New-Neuropathy (latest to develop
– A-Anemia with basophilic stippling
– B-Burtonian lines (blue lines over gums)
– C-constipation (most common symptom)
– D-dry belly (stomach ache without diarrhea)
– F-Facial pallor (first to appear)

# Mercury (Hg)-poisoning
– HgCl2 is the most toxic salt
– “Mn” Black TEA Le
– Black-blue lines on gums
– T-tremors (COARSE)—hands, arms, tongue, legs (appear last in legs); also called Danburry/Hatter’s/Glassblower’s tremors.
– E-Erethism—shyness, irritability, insomnia (social phobia)
– A-Acrodynia (Pink’s disease)
– Le-mercuria Lentis—bilateral brown pigmentation of cornea.
– “M” Mercury poisoning is also known as “Diwali” poisoning.

# “M” Toxins damaging PCT
– “Mn”=C-LMP
– Cadmium (tendency towards protenuria, rather than PCT necrosis)
– L-lysol
– M-mercury (tendency towards necrosis)
– P-phenol

# HCN poisoning
– Also known as prussic acid
– Ineffective when kept for a long time and when patient suffers from achlorhydria
– Potassium FERROcyanide is a NONtoxic salt
– Antidotes:
o Amyl nitrite
o Na-nitrite
o Na-thiosulphate
o PAPP-para-amino-propio-phenone
o All these drugs convert Hb to Meth-Hb. Cyanide (-CN) has higher affinity for Meth-Hb than for cytochrome oxidase. The complex thus formed is CyanMeth-Hb which gets transformed sequentially into thiosulphate and then thiocyanate. The last reaction is catalyzed by RHODANESE.

# Corrosive acids
– Sulphuric acid is most corrosive
– Alkaline antidotes used should be preferably NOT contain carbonates as they’d give rise to CO2 and lead to distention. E.g., CaO, MgO.

# Alcohol intoxication
– Formic acid-60x as toxic as methanol
– Formaldehyde-33x as toxic as methanol
– “Ep” Dry wine is chloral hydrate
– “EP” McEwan’s sign is used to distinguish alcoholic coma from other causes of coma—the constricted pupil dilates upon painful stimulus, and then constricts back GRADUALLY.
– “Ep”—Morbid jealousy found in acute alcoholic intoxication
– “M” Methanol fatal dose—60-250 mg.

# Opium poisoning
– Respiration becomes SLOW
– Stages of opium intoxication:
o Excitement-hallucinations + mania
o Stupor-vomiting, nausea, giddiness, headache, fatigability
o Coma-pinpoint pupil, headache, abolition of reflexes, respiratory depression, paralysis; “M” all secretions are stopped EXCEPT sweating.

# Mydriatic drugs:
– “Mn” Viper DANCE Party

– Viper-Viper poisoning
– D-dhatura
– A-aconite
– N-nux vomica (strychnine containing seeds)
– C-cocaine, cyanide, calotropis
– E-ether
– Party-pethidine

# OPP (organophosphate)
– Pink tears (chromodacryorrhea)
– Edematous lungs and asthma-like symptoms
– PAM (pralidoxime) is not effective against carbamates:
o “Mn” PD-CASED
o P-propoxur (baygon)
o D-Demecarium (veterinary anticholinesterase agent used for glaucoma)
o C-carbaryl
o E-edrophonium
o D-Donepezil (anticholinesterase used in Alzheimer’s)

# Barbiturate poisoning
– “M” pupils are constricted in barbiturate poisoning, but are still NOT pinpoint. They may dilate during terminal asphyxia.

# “M” Celphos—Aluminium phosphide—releases phosphine upon coming in contact with moisture. Phoshpine turns black on reacting with AgNO3 (silver nitrate). This is the basis of diagnosis of celphos poisoning. Phosphine gives garlic odor.

# “M” Chemical analysis of urine in forensics—best preservative-toluene; most commonly used—thymol.

# “M” Virological analysis—50% glycerol is used

# “M” Cantharies—Spanish fly/beetle—produces CANTHARIDIN

# Kerosene poisoning
– “M” pneumonitis may occur
– “M” X-ray features tend to appear much before the clinical signs.

# “M” Aconite fatal period 1-5 hours

# “M” Strychnine—all muscles are affected at the same time; anterior grey column of the spinal cord is affected.

# “M” Oxalic acid used as ink remover

# “M” Croton oil seed—fatal dose—20 drops

# Cocaine intoxication
– Antidotes:
– “M” formication also known as Magnan’s syndrome
o Phenobarbitone
o Benzodiazepines

# “M” Nux vomicaàstrychnine + brucine

# Copper poisoning
– Ptyalism (drooling)
– Fatal period 1-3 days.
– Urinary coproporphyrin level

# “M” Lead—least toxic salt is lead sulphide

# “M” Upper allowable level of atmospheric CO is 0.01%

# “M” Narcotic drugs and psychotropic substance act passed in year, 1985

# “M” Oxalate poisoning—antidote—calcium gluconate (Ca-gluconate)

# “M” Zinc—metal fume fever

———————-
> Obstetrics
* Obstetric anatomy
# Pelvis
– Diameters are measured at 3 levels:
o Inlet
o Midpelvis
o Outlet

o Inlet:
~ Anteroposterior—from sacral promontory to:
1. Superiormost point of symphysis—TRUE conjugate—11 cm
2. Midpoint of symphysis—OBSTETRIC conjugate—10 cm; cannot be measured directly but can be estimated by deducting 1.5 cm from diagonal conjugate. “M” Pelvis is considered CONTRACTED if obstetric conjugate is < 10 cm
3. Lowermost point of symphysis—DIAGONAL conjugate—12 cm

~ Transverse—13.0-13.5 cm—WIDEST dimension of the pelvis
~ Oblique—12 cm

– Midpelvis:
~ The plane of narrowest dimensions
~ AP diameter is 11.5 cm
~ “M” The interspinous (trandiameter is the NARROWEST dimension of the pelvis—10 cm; significance of interspinous diameter:
+ Level at which internal rotation occurs
+ Origin of levator ani muscle
+ Corresponds to station zero
+ Landmark for pudendal nerve block
+ Pelvis curves forward from this level

– Outlet:
~ AP—9.5-11.5 cm
~ Transverse (interTUBEROUS) diameter—11.0 cm
~ The transverse diameter divides the AP diameter into ANTERIOR and POSTERIOR SAGITTAL DIAMETERS of the OUTLET
~ “M” Posterior sagittal diameter of the outlet is a very important dimension and is usually > 7.5 cm

# “M” “EP” Pits on the posterior surface of pubis bone indicate past pregnancy and are known as “SCARS of parturition”

# “M” Transverse fetal diameters are always narrower than the AP diameters;
– “Mn” Increasing order of transverse diameters of fetal skull: Miss Tina So Pretty
– Miss-(bi)mastoid—7.5 cm
– Tina-temporal-8.0 m
– So-super subparietal 8.5 cm
– Pretty-parietal 9.5 cm

# Important embryologic events:
– First 14 days are known as PREORGANOGENESIS period—significance: any teratogenic insult would result in loss of pregnancy rather than malformations.
– 3rd to 8th week is known as the EMBRYONIC period; later it is known as the fetal period
– Important events by days:
o Day 2—two cell-stage
o 3—morula—16 cell stage
o 4—blastocyst
o 8—bilaminar (ectoderm and endoderm) disc is formed
o 14—prochordal plate and primitive streak are see
o 16—trilaminar (intraembryonic mesoderm) is formed

# “M” Decidua reaction occurs with implantation and involves intensification of secretory phase changes in the endometrium (implantation corresponds to about 22nd day of menstrual cycle, which involve thickening of the endometrium (epithelial cells becoming taller) and accumulation of glycogen. The thickness of endometrium at the time of implantation is 5-7 mm.

# “M” TRIPLE LINE—USG appearance of endometrium at the time of ovulation—9-10 mm.

# “M” Differences between preovulatory “surge” and “peak” of LH
– LH surge BEGINS 36 hours before ovulation
– LH peaks 12-15 hours before ovulation
o “M” LH peaks at 3 am in majority of women; peaks occur in evenings in winters, though.

# “M” Amnion produces peptides, growth factors and cytokines

# Intrauterine hematopoiesis
– Begins between 10th to 14th day in the yolk sac
– In the liver begins by 8 weeks
– Different sites produce different types of Hb:
o Yolk sac—Gowers type I and type II, and Portland
o Liver—Hb F
o Bone marrow—Hb A
o At 24th week, hepatic hematopoiesis is at peak: 90% Hb F, and 10% Hb A
o At birth: Hb F—70%; Hb A—30%
o “M” HbF is alkaline resistant
o Adult levels of Hb A are reached by sixth month of infancy
o Hb A2 reaches a constant level by the end of 1 year, thereafter the ratio of Hb A:Hb A2 tends to remain constant: 30:1

# Clotting factors in embryonic period:
– Fibrinogen production begins in about 5 weeks. This firbrinogen has the same aa composition as the adult one, but is less compressible and less aggregating.
– Production of other factors begins by around 12 weeks
– Levels of most of the factors tends to remain low in the umbilical cord, and hence vitamin K prophylaxis is essential.
– Low levels are found of: factors, II, VII, IX, X, XI, XII, XIII and fibrinogen; conversely, factors V and VIII are NOT deficient.

# Umbilical cord and placenta
– “M” “Ep”Hoboken folds are intimal folds of the umbilical artery in the umbilical cord
– “M” “Ep” Nitabuch’s layer is the zone of fibrinoid degeneration at the interface of trophoblast and deciduas
– “M” “Ep” Hoffbauer cells are the phagocytic cells in the connective tissue of the chorionic villi
– “M” Anatomically, the umbilical cord could be considered fetal membranes; the amnion wraps around the yolk sac, which can be seen as the whitish covering of the umbilical cord
– “M” Fetus : Placenta weight = 6 : 1 ; placenta weighs ~ 500 g
– Characteristics of human placenta:
o Discoid—shape
o Deciduate—shed at the end of parturition
o Hemochoroidal—maternal blood comes in contact with chorion

– Formation of placenta begins by 6th week and is completed by 12th week
– “Ep” Marginal insertion of placenta is known as BATTLEDORE placenta

# “M” Weight of normal uterus = 50 g (sic)
# “M” Intrauterine urine formation starts at 4 months
# “M”Fetal breathing movements begin at 11 weeks

————
* Physiologic changes during pregnancy

# System-wise physiologic changes during pregnancy:
– CVS:
o Cardiac output because of increased stroke volume increases (later the pulse rate also increases by about 10-15 bbpm)
o Decreased peripheral as well as pulmonary venous resistance
o Compression of IVC in supine position results in decreased venous return, stroke volume and CO. Lateral and “chest-knee” positions increase the CO
o Cardiac changes:
~ Both the ventricles enlarge because of increased blood flow through them, but there is no muscular hypertrophy
~ Left axis deviation
~ The cardiac apex shifts upwards into the fourth intercostal space and to the left (moves 2.5 cm away from the midclavicular line); the heart also rotates leftward.
~ There is a continuous murmur (called mammary murmur) in the tricuspid region
~ Systolic murmur because of increased flow across the aortic and pulmonic valves
~ S1 (both A1 and P1 become prominent) split becomes exaggerated
~ S3 becomes audible
~ S2 is Unaltered

– Hematologic changes
o Plasma volume increases by 50%, peaks by 32nd week of gestation
o RBC mass increases only by 30%, which leads to hemodilution—known as PHYSIOLOGICAL ANEMIA OF PREGNANCY
o Albumin is decreased, and globulin increases, so the albumin:globulin ratio falls from 1.7:1 to 1:1
o Fibrinogen is increased
o All the clotting factors except for XI and XIII increase. Factors XI and XIII DECREASE.
o Fibrinolysis decreases
o ESR increases four-fold.
o Neutrophilic leukocytosis occurs
o Thyroxine and TBG both increase

– Nutritional changes
o Serum lipids (triglycerides, phospholipids, cholesterol) increase
o Calorific demand increases by 15%
o Protein demand increases by 50%
o Vitamins A and C requirements also increase

– Renal
o Blood flow, and hence, GFR increase
o Clearance of urea, uric acid and creatinine increase
o AA and glucose are lost

– Respiratory
o Minute ventilation, conductance, oxygen absorbance and tidal volume increase
o Ventilatory capacity, forced ventilatory capacity and respiratory rate remain constant
o Residual volume, forced residual capacity decrease

– Substances that increase during pregnancy
o Fibrinogen
o Clotting factors II, V, VII, IX and X
o Globulin
o Transferrin (increased TIBC)
o Serum lipids
o Vitamin D3
o Estrogen
o Cortisol
o T3, T4 and TBG
o Leukocytes
o Calcitonin
o Insulin
o GH
o Total alkaline phosphatase
o CRP

– Substances that decrease during pregnancy
o Albumin
o Calcium
o Magnesium
o Potassium
o Sodium
o TSH
o Iron and ferritin
o Clotting factors XI and XIII
o Urea, uric acid, creatinine and BUN
o FSH and LH (because of increased estrogen)
o DeHydroAndrostenidione Sulphate (DHEAS)

– There is insulin resistance during pregnancy because of:
o Estrogen
o Progesterone
o Prolactin
o Cortisol
o Free fatty acids
o Human placental lactogen

– Increase in weight during pregnancy:
o First trimester—1 kg
o Second—5 kg
o Third—5 kg
o If weight increases more than 0.5 kg in a week, or more than 2 kg in a month

– Fetal growth:
o In utero fetal growth is independent of GH
o Insulin and IGF-1 required for linear growth

– Placental hormones
o Cytotrophoblast
~ Produces hypothalamus-like releasing factors
~ Corticotrophin releasing hormoe
~ GnRH
~ THRH
~ Neuropeptide Y

o Syncitiotrophoblast
~ Beta-HCG
~ Human chorionic thyrotropin
~ Pregnancy specific beta-1 glycoprotein
~ Pregnancy associated plasma protein A

o Other hormones
~ Relaxin—produced predominantly by corpus luteum, and also by placenta and deciduas
~ Estrogen and progesterone both produced by placenta using MATERNAL and fetal adremal cholesterol
~ Leptin—produced by both syncitio- and cytotrophoblast
~ Inhibin
~ Activin
~ TGF-beta
~ Epidermal growth factor
~ “M” Low amount of estriol indicates fetal compromise; low estriol is also a part of the triple test

# hCG
– “M” Alpha subunit is similar to other anterior pituitary hormones like LH, FSH and TSH. Functionally, it is most similar to FSH, but structurally most similar to LH. hCG

– Levels at various stages:
o Menses < 1000 mIU/L (97.5th percentile of background hCG level was found to be 1.2 IU/L)
o Becomes detectable at 5-8 days postfertilization by most sensitive radioimmunoassay (RIA)
o Peaks at 8 to 10weeks since LMP—1 00 000 mIU/L (1 lakh mIU/L) or 1000 IU/L (thousand-fold rise over baseline)
o Drops to 10 000 mIU/L by 18th to 20th week since LMP (a ten-fold drop from the peak). Thereafter the level remains constant throughout the pregnancy
o Reaches baseline two weeks after pregnancy

– Alpha subunit 18 kDa; beta subunit 28 kDa
– Increased level seen with:
o Hydatidiform mole
o Choriocarcinoma
o Multiple pregnancy
o Teratomas of ovary and testis
o Down’s syndrome
o Neoplasms of lung, stomach and pancreas

– Decreased level seen with:
o Ectopic pregnancy
o Trisomy 18
o Threatened/spontaneous abortion

– Functions:
o Sustains the corpus luteum
o Immune tolerance of pregnancy (known to induce apoptosis of lymphocytes)
o Induces testosterone production by Leydig cells in the male fetus

– Most SENSITIVE assay is the RADIORECEPTOR assay that has a sensitivity of 1 mIU/L (0.001 IU/L), but it crossreacts with LH
– Most SENSITIVE as well as SPECIFIC assay is RIA with iodine-125 that measures 2 mIU/L and doesNOT crossreact with LH
– “M” If urine hCG is negative during the first missed period, but pregnancy gets subsequently confirmed then USG estimation of age (and of EDD) become necessary as conception could have occurred later than would be usually expected

# Vaginal changes during pregnancy:
– Hyperemia—Chadwick’s sign
– Increased Lactobacilli—decreased pH—decreased chances of infection
– “Ep” Small cells called NAVICULAR cells seen in clusters
– “Ep” NAKED NUCLEI—nuclei without cytoplasm seen in abundance along with Lactobacilli

# “M” Despite increase in clotting factors and decrease in fibrinolytic activity, clotting time in the pregnancy remains normal

# “M” “Ep” ARIAS STELLA reaction
– Budding of glands
– Occasional mitoses
– Hyperchromatic nuclei
– Seen in 15% of pregnancies
– Indicates blighting of conceptus
– Occurs under the influence of progesterone
– “M” decidual reaction occurs under the influence of both estrogen and progesterone

# Uterine soufflé:
– Soft systolic murmur
– Heard best on the left side

# FETAL or FUNIC soufflé is heard because of flow through the fetal umbilical arteries, and is synchronous with FHS

# Prolactin
– Synthesized by deciduas
– Highest level found during pregnancy, and level keeps on falling after delivery even in the lactating mothers
– Also found in the amniotic fluid, where the highest level of 10 000 ng/mL is found around 26th week, following which the levels keep on falling till the 34th week and plateau
– Pregnant blood level is 150 ng/mL which is 10 times higher than the baseline

# Human Placental Lactogen
– Also called Human chorionic somatomammotrophin
– Synthesized by syncitiotrophoblast
– Becomes detectable by 5th week and levels keep on rising till the 36th week
– In mother causes lipolysis, and thus increase in FFA level
– Causes insulin resistance
– Promotes angiogenesis in the fetus; fetal growth rate is related to exponentially to its concentration

# Time of appearance of various hormones:
– Glucagon—8 weeks
– Anterior pituitary hormones—10 weeks
– Thyroid—11 weeks
– Posterior pituitary hormones—12 weeks
– Insulin—12 weeks

# Thyroid in pregnancy
– Thyroid enlarges
– Total levels of both T3 and T4 increase, but free levels do not increase as TBG also increases.
– Protein bound iodine (PBI) increases from ~ 6 ug to 10 ug
– Daily iodine requirement increases from 150 ug to 200 ug
– Very little thyroxine crosses over to the fetus
– Calcitonic concentration increases by 20%

# Iron content of the breast milk is 1 mg/L (iron:milk ratio is 1:1 million or 1:1000000)
# “M” Increase in fetal cortisol results in release of oxytocin and uterince contraction, through increased production of estrogens and prostaglandins
# Uterine blood flow at term is 750 mL/min (Clue to remember: slightly more than the renal blood flow)
# “M” Breast milk can be expressed by squeezing as early as 12th week of pregnancy

# Clinical signs in pregnancy:
– Jacquimer’s/Chadwick’s sign—8 weeks—bluish discoloration of vestibule and anterior vaginal wall because of congestion—also seen in fibroid
– Osiender’s sign—8 weeks—increased pulsatility found flanking the lateral fornices—also seen in PID
– Goodell’s sign—6 weeks—the cervix feels like the tip of a mouth as compared to the tip of nose because of softening
– Hegar’s sign—6 to 10 weeks—softening of isthmus as confirmed by bimanual examination
– Palmer’s sign—6 weeks —rhythmic contractions of the uterus as felt on bimanual exam
– Ladin’s sign—6 weeks —uterus softens at the uterocervical junction
– McDonald’s sign—8 weeks —uterocevical junction becomes more flexible
– Von Fernwald’s sign—4 to 5 weeks—softening of the uterine fundus

– Size of uterus at:
o 6th week—egg size
o 8th week—cricket ball size
o 12th week—fetal head size

# Chronology of gestational events:
– Braxton Hicks (named after British obstetrician John Braxton Hicks [single scientist]) contractions begin by 6th week and last till labor, but are usually not appreciated by the mother before second trimester
– 16 weeks—fetal skeleton becomes visible radiologically
– 18 weeks
o FHS become audible through the stethoscope
o Quickening (fetal movements felt by mother) in primi; in multi this appreciation begins two weeks earlier
– 18 to 20 weeks—ballottement of uterus
– 20 weeks
o Palpation of fetal parts
o Breast changes
o Linea nigra appears
– 24 weeks—chloasma
– Lightening occurs by around 38th week

# Estimation of fetal age by USG:
– Best time is between 9-12 weeks by measuring the CRL
– Best method to estimate age in second and third trimesters is by measuring the head circumference
– Other methods that can be used in both second and third trimesters are corrected biparietal diameter (BPD) and abdominal circumference
– Femoral length (FL) is used only in the third trimester
– “M” In third trimester, FL + 6.5 cm = age in weeks
– “M” Intercereberallar diameter in mm = age of the fetus in weeks (between 14 and 24 weeks)

# Gestational sac:
– First sonographic sign to confirm pregnancy
– Appears around 14 to 17 days from fertilization or around 5 weeks from LMP
– Its appearance coincides with the knowledge of first missed period and positive results by hCG measurement in urine by dipstick, but ~ 5 to 6 days after hCG surge can be measured by the most sensitive RIA methods
– True gestational sac can be differentiated from pseudo gestational sac by:
o Eccentric (v/s central) location of implantation
o Presence of double ring sign because of chorion
o Growth rate of 1 mm/day
o Visualization of yolk sac and fetal pole

– “Ep” When the conceptus implants, initially, it does not deform the central empty cavity of the uterus and this is called the INTRADECIDUAL SIGN; later when due to growth this cavity is deformed, it is known as DOUBLE DECIDUAL SAC SIGN

# Risk factors for neural tube defects:
– Type I DM
– Treatment with valproate and carbamazepine
– Prophylactic dose of folate is 400 ug; but for those with past incidence of NTDs it is 4 mg (10 times higher)

# Fetal heart rate:
– 6 weeks—100 to 115 bpm
– 8 weeks—140 to 160 bpm
– Later in pregnancy—120 to 140 bpm

# “M” Pseudocyesis—false pregnancy, usually seen as a psychiatric symptom in infertile women. Enlargement of the abdomen is the most common symptom seen

# “M” Physiologic edema of pregnancy is the edema limited to the lower limb because of decreases venous return through the femoral veins owing to increased pressure in upright position (pressure in pregnant state is found to 80 to 100 cm of water as compared to 8 to 10 cm of water in the nonpregnant state). The only treatment required is bed rest, as that would facilitate venous return

# RDA during pregnancy:
– Nutrient | Normal requirement (N) | Pregnant state (P) | Lactation (L)
– Energy | 2200 (N) | 2500 (P) | 2650 (L)
– Protein | 50 g (N) | 65 g (P) | 75 g (L)
– Fat | 20 g (N) | 30 g (P) | 45 g (L)
– Calcium | 500 mg (N) | 1000 mg (P) | 1500 gm (L)
– Iron | 30 mg (N) | 40 mg (P) | 30 mg (L)
– “M” Iron is the only nutrient, the increased RDA of which cannot be completely satisfied by dietary supplementation alone

# Fetal indices of malnourishment:
– Best indicator is abdominal girth, which is measured at the level of the bifurcation of the hepatic vessels in the fetal liver
– Head circumference is the last to get affected due to malnourishment, so if it is reduced, the malnourishment is severe
– “M” Head circumference is measured at the level of thalami
– HC:AC ratio, if very high, is a strong indicator of severe and longstanding malnourishment as head circumference is the last to get affected
– Femur:abdomen circumference ratio remains constant at 22 weeks at 22 + or – 2
– Fetal Ponderal index (FPI) = estimated fetal weight / cube of femoral length; it is usually = 8.325 + o r – 0.25; FPI < 7 strongly suggests fetal retardation of growth
– Oligohydramnios can be one of the manifestations of fetal malnourishment
– Amniotic fluid index is calculated by adding the depths of four fluid pockets; 20 cm—polyhydramnios

————–
* Labor

# Prelabor changes:
– Lightening—occurs due to formation of the lower uterine segment
– Cervical ripening. Induced by oxytocin; under the influence of estrogen the oxytocin receptors increase

# “M” Pelvic assessment is done just before the onset of labor

# Cardinal movements of labor:
– Engagement
– Descent
– Flexion
– Internal rotation
– Crowning
– Extension
– Restitution
– External rotation
– “M” crowning is not a cardinal “movement” in the rigorous sense of the term

# “M” Cephalic presentation is the most common one (95%)
# Head enters the pelvic inlet through:
– Transverse diameter—75%
– Oblique diameter—20%
– AP diameter—5%
– This is known as the DIAMETER of ENGAGEMENT

# Most common lie is LEFT occipital TRANSVERSE (and NOT left occipital FRONTAL)

# ENGAGING DIAMETER is the AP diameter of the fetal skull that enters the pelvic inlet. Most commonly it is suboccipitobregmatic (9.5 cm)—fully flexed or suboccipitofrontal (10.0 cm)—slightly deflexed

# Stages of labor:
– I
o From the beginning of labor pains to complete cervical dilation
o Primi: 12 to 16 hours
o Multi: 8 to 12 hours
o Latent phase is the preparatory phase during which most of the cervical changes take place and lasts till cervical dilation of 3 cm
o Active phase:
~ Rate of dilation: primi—1.2 cm/h; multi—1.5 cm/h
o The ratio of duration of latent:active phase in both primi and multi is ~ 1:1

– II
o From complete cervical dilation to complete expulsion of the fetus
o Takes 0 to 4 hours in both primi and multi

– III—expulsion of both placenta and fetal membranes—takes about 15 min normally, and 10 min with active management

# Prolonged latent phase
– Primi: > 20 h; multi > 14 h
– Causes:
o Excessive sedation or analgesia
o Incomplete formation of the lower uterine segment
o Wrongly thinking false labor to be true labor

– “M” Diagnosis of prolonged labor is made by Friedman’s curve
– Treatment is by giving rest, or by uterine stimulation by giving oxytocin

# Engagement
– Definition—the widest transverse diameter of the fetal skull (biparietal diameter) crosses the pelvic inlet, it is known as engagement.
– “M” Engagement occurs earlier in prim at around 38th week, whereas it occurs just with the onset of labor in multi (after the rupture of membranes)
– “M” “Ep” Clinically, CRICHTON method is used to estimate the degree of engagement of the fetal head
o Fifths of head as palpated per ABDOMINALLY are used to estimate the degree of engagement; more the fraction of head palpable, LESS the degree of engagement
o 5/5—floating
o 4/5—brim
o 3/5 and 2/5—not engaged
o 1/5—engaged
o 0/5—deeply engaged

– Commonest cause of nonengagement in primi—CPD
– Causes of nonengagement in multi:
o CPD
o Malpresentation
o Neck tumors
o Hydrocephalus
o Cord around neck
o Polyhydramnios
o Lower segment tumors
o Distention of bladder and rectum
o Deflexed head
o Occipitoposterior postion
o Placenta previa

# Bishop score includes
– First three parameter—cervical dilation, effacement and station have scoring from 0 to 3, and the last two—cervical consistency and position have scores from 0 to 2; thus minimum possible score is zero and maximum possible score is 19
– A score of 10 or more portends good result with active management
– Cervical dilation
– Effacement
– Station
– Consistency of cervix
– Postion of cervix

– Cervical dilation:
o 0: closed
o 1: 1 to 2 cm
o 2: 3 to 4 cm
o 3: > 5 cm

– Effacement:
o 0: 0 to 30 %
o 1: 30 to 50
o 2: 50 to 80
o 3: > 80

– Station:
o 0: -3
o 1: -2
o 2: -1
o 3: > -1

– Cervical consistency:
o 0: firm
o 1: medium
o 2: soft

– Cervical position:
o 0: posterior
o 1: midposition
o 2: anterior

# Partogram:
– Graph contains:
o Rate of cervical dilation
o Station
o Molding
o Rate of uterine contraction (per 10 min)
o Maternal pulse rate and blood pressure
o Maternal temperature
o Urine: volume, acetone and proteins
o Oxytocin units administered
o IV fluids and drugs administered

– Latent phase is expected to be completed by 8 h, beyond which a line called the ALERT line is drawn—the slope of which is 1 cm/h
– ACTION line is drawn 4 h to the right of the alert line
– If alert line is crossed at a peripheral center, the patient should be immediately transferred to a tertiary center. If it is crossed in a referral center, then intervention should begin

# Estrogen v/s progesterone on uterus
– Estrogen:
o Increases myometrial stroma
o Leads to synthesis of myosin through cAMP
o Increases the frequency of action potentials
o Increases sensitivity to oxytocin

– Progesterone:
o “M” Decreases the frequency of action potentials, but increases the amplitude
o Aids estrogen in myometrial hypertrophy
o Causes deposition of glycogen and lipids

# Friedman’s curve:
– Latent phase ends at 3 cm of cervical dilation
– Active phase is divided into:
o Acceleration phase—3 to 4 cm (1 cm in all)
o Phase of maximum slope—4 to 9 cm
o Deceleration phase—9 to 10 cm (1 cm in all)

# Abnormalities of ACTIVE phase of labor:
– Prolonged labor in primi—rate of dilation < 1.2 cm/h, and rate of descent < 1 cm/h
– Prolonged labor in multi—rate of dilation < 1.5 cm/h, and rate of descent < 2 cm/h
– Arrest of dilation—no dilation for more than 2 hours
– Arrest of descent—no descent for more than 1 hour
– Precipitate labor:
o In nulliparous—rate of descent or dilation > 5cm/h
o In multiparous—rate of descent or dilation > 10 cm/h

# Layers of myometrium:
– Innermost is of circular muscles
– Outermost is of longitudinal
– “Ep” middle layer is of intermediate fibers that are crisscross, and as it contains blood vessels and occludes them upon contraction it is also called LIVING LIGATURE.
– Layers can be remembered as |XOX| that is circular in the center, crisscrossed in between and vertical fibers outside

# Signs of placental separation:
– Uterine signs:
o Uterus become firm, globular and ballottable—FIRST sign to appear
o “Ep” Fundal height increases slightly because the placenta enters the lower segment upon which the uterus now rests—SHROEDER’S SIGN
o Slight suprapubic bulging because of placenta entering the lower segment
o “Ep” On pulling the fundus upwards the umbilical cord does not shorten (as the placenta is now in the lower segment and DETACHED from the original site of attachment to the uterine wall)—KUSTNER’s SIGN

– Vaginal signs are gushing of blood and permanent shortening of the umbilical cord
– “M” Crede’s method is not to be used; controlled cord traction of modified Andrew’s method is to be used

# Rupture of membranes:
– Membranes usually rupture just after complete cervical dilation
– PREMATURE RUPTURE—when rupture occurs before the ONSET OF LABOR
– EARLY RUPTURE—when rupture occurs before COMPLETE CERVICAL DILATION
– “M” “Ep” Sometimes when membranes do NOT rupture at all and they cover the mouth of the newborn, then the baby is said to be born in a CAUL

# EDD:
– Percentage of deliveries on EDD—4%
– Within 1 week of EDD (EDD +/- or ± 1 week)—50%
– Within 2 weeks of EDD (EDD ± 2 weeks)—80%
– Delivery at 42 weeks—10%
– Delivery at 43 weeks—4%

# True v/s false labor:
– True labor is felt in abdomen, back and RADIATES to the thighs; false labor is felt only in the lower abdomen, and may END WITH ENEMA

# Force of contraction during labor:
– First stage: 40 to 50 mm Hg
– Second stage: 100 to 200 mm Hg

————–

* Malpresentations

# Breech presentation:
– “M” Frank breech is most common in primi
– “M” Prematurity is the most common cause
– “M” Presentation during pregnancy:
o At 28 weeks 20% or presentations are breech
o Spontaneous version occurs between 30 to 34 weeks such that by term only 3% breech presentations persist

– Breech presentation may not convert to vertex because of:
o Factors preventing spontaneous version
o Factors promoting breech—where breech presentation is a mode of adaptation
o Because of excessive mobility available to the fetus

– Factors preventing spontaneous version:
o Prematurity
o Oligohydramnios
o Short cord
o Twins
o Uterine malformations like bicornuate uterus
o IUD
o Breech with extended legs

– Factors where breech is a mode of adaptation:
o Hydrocephalus
o Placenta previa
o Cornuofundal attachment

– Factors affording excessive mobility to the fetus are polyhydramnios and lax abdomen in a multipara
– “M” RECURRENT breech is one where 3 or more breech presentations have occurred, and can be caused by uterine anomalies or recurrent cornuofundal attachment
– Most common type of breech is frank breech (also called Pike position)—seen in 50 to 70% cases; incomplete breech is seen in 10 30 % cases, and complete breech (also called cannonball position) is seen in 5 to 10 % cases

– Engaging diameters:
o Buttocks—intertrochanteric diameter—10 cm
o Shoulders—interacrimial diameter—12 cm
o Head—suboccipitofrontal diameter—10 cm

– External cephalic version (ECV)—done after 35 completed weeks; best time is 36th week
o Contraindications:
~ Eclampsia/hypertension
~ APH
~ Placenta previa
~ Bad obstetric history
~ Contracted pelvis
~ Oligohydramnios
~ Uterine anomalies
~ Elderly multigravida
~ Hyperextended head
~ IUGR
~ Dead fetus

– Footling breech is with flexed head is the best candidate for vaginal delivery
– Vaginal delivery in breech presentation may occur in 3 circumstances:
o Spontaneous breech delivery—entire delivery occurs through spontaneous expulsive efforts of the uterus
o Assisted vaginal delivery—the fetus is spontaneously expelled till the level of the umbilicus, whereupon, further maneuvers are employed to deliver the rest of the body
o Total breech extraction—the feet are grasped and the entire fetus is extracted; this is employed ONLY for second NONCEPHALIC TWIN. It must NOT be used in singleton pregnancies
o Oxytocin is not to be used as it may push the fetal head against INCOMPLETELY dilated cervix

– Assisted breech delivery:
o Leg—Pinard maneuver:
~ Used for delivery of legs in FRANK breech
~ Pressure is applied behind the fetal knee, which prompts the fetus to flex the knee
~ By applying traction over the other foot, which is brought into the midline, the baby is delivered
~ “M” Adolphe Pinard after whom the maneuver is named is also credited to have developed the first fetal stethoscope

o Arms—Lovset’s maneuver—baby is rotated half a circle so that the posterior arm becomes the anterior arm, and then it is flexed at the elbow such that the hand is positioned opposite the baby’s face. All the while traction is also applied by gripping the baby’s hips. The same procedure is repeated for the second arm
o Head:
~ Burns Marshall Method—the fetal ankles are grasped and rotated while the body is spontaneously delivered
~ Mauriceau-Smellie-Veit method—has many components, all aimed at bringing the fetus’ head in a flexed position:
+ The fetus’s face faces posteriorly (downward on a table)
+ Index and ring fingers are used to apply downward traction by placing them on the malar prominences, and the middle finger is used introduced in the mouth to pull down the lower jaw
+ Suprapubic pressure is applied by the assistant to keep the head in flexed position
+ Gentle traction is applied to the shoulders
~ Piper’s forceps

– “M” Chin to pubis—it is a complication of the breech delivery wherein the fetus turns anteriorly and the head chin impacts against the top surface of the pubes, which is VERY DIFFICULT TO DELIVER; to deliver the fetus is gently turned posteriorly and Mariceau maneuver is performed; if the baby is premature, the delivered feet are also drawn up into its abdomen apart from performing the Mariceau maneuver

– Entrapment of head in breech:
o Causes:
~ Incomplete cervical dilation
~ Hydrocephalus
~ Extended head
o Management is by putting multiple incisions on cervix called DURRHSEN’s INCISIONS barring the 3 O’ clock and 9 O’ clock positions. IV nitroglycerine, Zanavelli procedure as well as symphisiotomy may also be tried.
o Impaction can occur at the level of inlet outlet, or midpelvis. And, from the time of complete cervical dilation, if breech does not distend the perineum within 30 min, CS should be performed

# Deep transverse arrest:
– The sagittal suture of the fetal head is arrested in the transverse diameter at the level of the ischial spines in spite of good uterine contractions and complete cervical dilation

# Transverse lie:
– ECV may be tried if the gestation is beyond 35 weeks
– LSCS is preferred if the back is anterior or inferior
– In LSCS a lower “J”-shaped incision may be tried
– “M” Internal podalic version is reserved only for the delivery of the second twin

# Destructive procedures for dead fetus:
– For neglected shoulder dystocia:
o Cleidotomy
o Spondylotomy—division of vertebra
o Evisceration or embryotomy—removal of viscera from abdomen

– Location of craniotomy for various presenting parts:
o Vertex—one of the parietal bones
o Brow—forehead
o Face—Orbit or roof of the mouth
o Aftercoming head of breech—occipital bone

# Occipitoposterior position:
– Causes:
o Anthropoid pelvis—AP diameter is greater than the transverse diameter; many times there is extra sacral vertebra, which increases the inclination of the pelvis
o Android pelvis—wedge shaped
o High inclination of the pelvis
o Anterior attachment of the placenta
o Brachycephaly
o Abnormal uterine contractions

– Possible mechanisms of labor
o Anterior rotation: occiput rotates anteriorly by 3/8th of a circle and labor is delayed because of deflexion of the head
o Posterior rotaion: occiput abuts against sacrum, and sinciput faces the pelvic floor—delivery proceeds as face-to-pubes presentation

– Possible complications:
o Perineal tear as the biparietal diameter (9.4 cm) instead of the bitemporal diameter (8 cm)
o Due to extreme molding, the falx cerebrii gets elevated and tentorial tear may occur.

– Management: if occiput is:
o Below ischial spines—vaginal delivery with forceps
o Above ischial spines—CS

# “M” Vaginal delivery is IMPOSSIBLE in MENTOPOSTERIOR position, whereas it is DIFFICULT in occipitoposterior position, but POSSIBLE, as it can occur as face-to-pubes delivery
# “M” Most common anomaly with face presentation is ANENCEPHALY