Fetal membranes 2
This presentation is the property of its rightful owner.
Sponsored Links
1 / 24

Fetal Membranes 2 PowerPoint PPT Presentation


  • 119 Views
  • Uploaded on
  • Presentation posted in: General

Fetal Membranes 2. Dr Rania Gabr. Objectives. By the end of this lecture, the student should be able to: Describe the structure, functions, anomalies of the placenta Describe the structure, functions, anomalies of the umbilical cord. PLACENTA. SHAPE: circular disc

Download Presentation

Fetal Membranes 2

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Fetal membranes 2

Fetal Membranes 2

Dr Rania Gabr


Objectives

Objectives

By the end of this lecture, the student should be able to:

  • Describe the structure, functions, anomalies of the placenta

  • Describe the structure, functions, anomalies of the umbilical cord


Placenta

PLACENTA

  • SHAPE: circular disc

  • WEIGHT: about one-sixth that of fetus (500-600 gm)

  • DIAMETER: 15-20 cm

  • THICKNESS: 2-3 cm

  • SURFACES:

    1. Fetal surface:

    smooth, transparent, covered by amnion with umbilical cord attached near its center & umbilical vessels radiating from it

    2. Maternal surface:

    irregular, divided into convex areas (cotyledons)


Placenta1

PLACENTA

  • The fetal part of placenta is divided into cotyledons by projections from decidua basalis(placental septa)

  • Each cotyledon contains 2 or more stem villi with their branch villi

  • By the end of 4th month, decidua basalis is almost entirely replaced by cotyledons


Placental circulation

PLACENTAL CIRCULATION

  • Poorly oxygenated blood leaves the fetus & passes through the 2 umbilical arteries to the placenta

  • Umbilical arteries divide into several chorionic arteries that enter chorionic villi

  • An arterio-capillary-venous network is formed in chorionic villi

  • Exchange of materials between fetal & maternal blood (in intervillous spaces) occurs across placental membrane (barrier)

  • Oxygenated blood returns to fetus by umbilical vein


Functions of the placenta

Functions of the Placenta

  • Exchange of metabolic & gaseous productsbetween maternal & fetal bloodstreams

    • Respiratory function: Exchange of gases –

    • Nutritive function: Exchange of nutrients & electrolytes –

    • Transmission of maternal antibodies –

    • Excretory function: Co2 and other stuff

  • Barrier function: prevents passage of some bacteria and some drugs from maternal to fetal blood.


Fetal membranes 2

  • Endocrine function: Production of hormones

  • Protein hormones:

  • Human chorionic gonadotropin(early pregnancy tests)

  • Human placental lactogen

  • Human chorionic thyrotropin

  • Human chorionic corticotropin

  • Relaxin

  • Steroid hormones:

  • Progesterone

  • Estrogen


Anomalies of placenta

ANOMALIES OF PLACENTA

  • ANOMALIES IN SIZE & SHAPE:

  • Normally chorionic villi persist only at site of decidualbasalis:

  • Placenta membranacea: a large thin membranous placenta due to persistence of functioning villi on the entire surface of chorionic sac

  • Accessory placenta: a patch of chorionic villi persisted a short distance from main placenta


Accessory placenta

ACCESSORY PLACENTA


Placenta previa accreta percreta

PLACENTA PREVIA, ACCRETA & PERCRETA


Anomalies of placenta1

ANOMALIES OF PLACENTA

  • ANOMALIES IN POSITION:

  • Placenta previa: when blastocyst implants close to or overlying internal os of uterus late pregnancy bleeding

  • ANOMALIES IN EXTENSION:

  • Placenta accreta: chorionic villi extend to the myometrium

  • Placenta percreta: chorionic villi penetrate the whole thickness of myometrium & extend to perimetrium


Anomalies of placenta2

ANOMALIES OF PLACENTA

  • ANOMALIES IN ATTACHMENT OF UMBILICAL CORD:

  • Battledore placenta: the cord is attached to the margin of placenta

  • Velamentous insertion of cord: the cord is attached to the membranes surrounding placenta, umbilical vessels are liable to be ruptured


Fetal membranes 2

Battledore placenta

Velamentous insertion of cord


Umbilical cord

Umbilical Cord

  • Cord like structure

  • Connects fetus to the placenta

  • Attached to the ventral surface of the fetal body and to the smooth chorionic plate of the placenta


Umbilical cord formation

Umbilical Cord: Formation

  • Develops from the connecting stalk

  • The connecting stalk initially attached to the caudal end of the embryonic disc, after folding, becomes attached to the ventral surface of the curved embryonic disc, at the umbilical region

  • Theumbilical region wider initially, becomes narrower as the folding progresses

  • The underlying structures are compressed together and form a cord like structure, the umbilical cord


Umbilical cord formation cont d

Umbilical Cord: Formation cont’d

  • Initial contents:

    • Connecting stalk

    • Umbilical vessels

    • Allantois

    • Yolk sac

    • Extraembryoniccelome

    • Intestinal loop (during 6-10 weeks)


Umbilical cord at term

Umbilical Cord: At Term

At term, the typical umbilical cord:

  • Is 55-60 cm in length,with adiameter of 2-2.5 cm

  • Hasknottyappearance

  • Usually contains two arteriesandone vein

  • Issurrounded by a jelly like substance called the Wharton's jelly

  • Is enclosed in amnion

amnion


Umbilical cord placental attachment

Umbilical Cord: Placental Attachment

May attach to the placenta near its margin- Marginal attachment

Typically attaches to the placenta near its center- Eccentric attachment

placenta

May attach to the membranes around the placenta- Membranous (Velamentous ) attachment


Umbilical cord cont d

Umbilical Cord cont’d

  • After delivery of the placenta the umbilical cord is usually clamped and severed

  • The site of its attachment leaves a scar, the navel (belly button), on the anterior wall of the abdomen


Abnormalities related to umbilical cord

Abnormalities Related to Umbilical Cord

  • Omphalocele: Failure of returning of intestinal loops back into the abdominal cavity

  • Long cord may prolapse or coil around the fetus thus cause difficulty in labour

  • Short cord may result in premature pull and separation of placenta causing severe bleeding during birth

  • True knots

True knot

Prolapsed cord


Fetal membranes 2

Thank You & Good Luck


  • Login