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Umbilical Cord

  1. The average length of umbilical cord is 37-50 cm.
  2. The cord has three vessels: 1 vein and 2 arteries. The right vein disappears (the left is left).
  3. The O2 supply to the fetus is at the rate of 5 mL/kg/min and this is achieved with cord blood flow of 165-330 mL/min.

Variations of Umbilical Cord

  1. Cord length at term has appreciable variation, and extremes range from no cord (achordia) to lengths up to 300 cm.
  2. Single umbilical artery
    1. It is seen in 0.7-0.8% cases of single pregnancy and 5% of twin pregnancy
    2. More common in diabetic patients, black patients, with eclampsia, hydramnios and oligohydramnios, epilepsy patients and in APH.
    3. Finding of a single umblical artery is not insignificant and is associated with:
      Congenital malform actions of the fetus in 20-25% cases amongst which Renal anomaties. Genitourinary anomalies and Trisomy 18 are common.
      Increased chances of abortion, prematurity, IUGR and perinatal mortality.
  3. Battledore placenta: Cord insertion at the placental margin is referred to as a battledore placenta.
  4. Velamentous insertion: The umbilical vessels separate in the membranes at a distance from the placental margin, which they reach surrounded only by a fold of amnion.
  5. Vasa previa
    1. This finding is associated with velamentous insertion when some of the fetal vessels in the membranes cross the region of the cervical os below the presenting fetal part.
    2. Marginal cord insertions and bilobed or succenturiate-lobed placentas are also associated with vasa previa.
    3. Color Doppler is the investigation of choice.
    4. With vasa previa, there is considerable potential fetal danger because membrane rupture may be accompanied by tearing of a fetal vessel. This is a/w very high perinatal mortality as there is exclusive fetal blood loss.
    5. Low-lying placenta is a risk factor in 80% of cases.
    6. Patients of vasa previa should be delivered by elective LSCS.

Abnormalities of the cord





The umbilical cord is attached to the placenta near the centre



Cord is attached to the margin of the placenta (this type of placenta is called Battledore placenta.



Here the blood vessels divide before reaching the placenta.



Here the blood vessels are attached to the amnion, where they ramify before reaching the placenta.



Short Cord is associated with

Excessively long cord is associated with

  • IUGR
  • Abnormal lie/presentation
  • Congenital malformations
  • Pre nature placental
  • Cord entanglement
  • Cord around the neck of fetus
  • Fetal distress
  • Cord prolapse
  • Fetal anomalies


Extra Edge:


Here are few other named structures frequently asked and the organ / structure where it is found.

Named Structure

Seen in

Nitabuch’s layer

It is the zone of fibroid degeneration where trophoblast and decidua meet. Seen in basal plate of placenta.

Hofbauer cells

Phagocytic cell seen in connective tissue of chorionic villi of placenta

Folds of Hoboken

Umbilical cord

Wharton’s jelly

Connective tissue of umbilical cord

Peg cells

Fallopian tube

Langhans cells


Amniotic Fluid

  1. pH of amniotic fluid is 7.0-7.5.
  2. The fetus swallows about 400 mL of liquor daily at term.
  3. The volume of amniotic fluid at term is 800 mL.
  4. An osmolarity of 250 mOsmol/L of amniotic fluid is suggestive of fetal lung maturity.
  5. Fetal urine is the major component of amniotic fluid.

Weeks of Gestation

Quantity of Amniotic Fluid (ml.)














Color of Amniotic Fluid

Clinical Importance


 Pre term

 Straw colored


 Meconium stained

 Fetal distress


 Rh incompatibility

 Amber / saffron


 Blood stained

 Abruptio placenta

 Tobacco juice






AF is also measured as largest vertical pockets in each of the four quadrants of uterus

AFI (normal)


approx 1000 ml

Single largest Pocket2-8 cm   

AFI (oligo H)


approx 500 ml


AFI (Poly H)


approx 2000 ml



Oligo H

Poly H

AFI <5


Largest single pocket < 2cm


Liquor <500ml (<200ml at term)


Incidence is rare



  1. Unknown
  2. GCMF Baby
  3. Drugs (NSAIDS, ACEI)
  4. Fetal Renal agenesis
  5. IUGR with placental insufficiency
  6. Amnion nodosum


  1. Unknown 60%
  2. GCMF Baby 20%
  3. Chorioangioma of placenta
  4. Maternal factors – Multiple pregnancy , DM, RH-ve
  5. PIH (25%)
  6. Perinatal Mortality 50% because of prematurity and GCMF.
  7. Drug of choice (Medical management) – INDOMETHACIN 25mg QID till 32-34 weeks with follow up with fetal ECHO because of risk of premature ductal closure leading to TR.

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