FETAL CIRCULATION

➦ Definition:

Fetal Circulation or Foetal Circulation refers to the unique circulatory system that allows the exchange of gases and nutrients between the developing fetus and the pregnant mother.

Fetal Circulation Diagram

➦ Umbilical Cord:

        ● Umbilical Arteries:

Bring Oxygenated blood and nutrients to the fetus.

➦ Shunts:

       ● Ductus Venosus:

Connects the umbilical vein and inferior vena cava.

       ● Ductus Arteriosus:

       ● Foramen Ovale:

➦ Cardiac Output:

• During fetal life – 350 ml/kg/min
• Following birth – 500 ml/kg/min

➦ Fetal Heart Rate;

The normal fetal heart rate is 120 – 160 beats/min.

➦ Fetal Circulation Flow Chart:

 

Fetal Circulation Flow Chart

 

➦ Fetal Circulation Explained Video:

 

 

➦ Download NOTE of Fetal Circulation:

Uterine Fibroids

Definition of Fibroid:

Fibroid tumors are benign tumors arising in the myometrium which can protrude into the uterine cavity, bulge through the outer layer or grow within the myometrium.

Growth of Fibroids

1. Fibroids develop due to proliferation of smooth muscle cells. The tumors usually grow very slowly, about 1 to 2 cm per year.

2. Fibroids are estrogen dependent and thus grow rapidly during pregnancy. They do not occur before menarche and growth cessation occurs after menopause.

Types of Fibroids:

Alternatively named myomata or leiomyomata, uterine fibroids are the commonest of all pelvic tumors. They are benign fibromuscular swellings, arising in the muscle wall of the uterus. Fibroids are oestrogen sensitive.

➦ Submucous: It lies immediately below the endometrium and enlarges the surface of the uterine cavity often leading to menorrhagia. Fibroids may become pedunculated forming polypi which can extrude through the cervix.

➦ Intramural: The commonest site for fibroids, surrounded by smooth muscle, enlarging the uterine wall and distorting venous drainage.

➦ Subserous: Fibroids just beneath the peritoneum on the outer uterine surface. May be on an elongated stalk (pedunculated) with a risk of torsion; may grow into the broad ligament.

Clinical Features of Fibroid:

1. Majority of fibroids (75%) remains asymptomatic and are detected during routine examination or at laparotomy or laparoscopy.

2. The uterus reaches a 4 to 5 months gestation size without symptoms in most cases.

3. In symptomatic type, menorrhagia is the classic symptom.

4. Metrorrhagia or irregular bleeding is seen in some women.

5. Dysmenorrhea is a symptom when it is associated with pelvic congestion or endometriosis.

6. Infertility is seen in about 30 percent of women.

7. Recurrent pregnancy loss (Miscarriage or preterm labor).

8. Lower abdominal or pelvic pain.

Symptoms of Fibroid:

• • None: a pelvic swelling is found incidentally on examination.
  • Occasional tightness of waistband of clothes.
  • Pressure: bladder compression causing daytime frequency and occasionally impaired urinary stream. In the supporting ligaments it causes backache and overall sensation of pelvic heaviness.
  • Pain: associated with red degeneration or torsion of subserous pedicles. Dysmenorrhoea may indicate the presence of a submucous fibroid.
  • Menstrual disturbances:

a. Menorrhagia: heavy bleeding;
b. Metrorrhagia: prolonged menses;
c. Irregular, intermittent bleeding: often associated with polyps and other surface lesions.

Diagnosis of Fibroid:

1. Majority of uterine fibroids can be diagnosed from S history and pelvic examination

2. Ultrasound and color Doppler are used to locate the fibroids accurately.

3. Laparoscopy is useful if the uterine size is less than 12 weeks and associated with pelvic pain and infertility

4. Uterine curettage is done in the presence of irregular bleeding to detect any coexisting pathology and to study the endometrial pattern.

Differential diagnosis

• Pregnancy: particularly if fibroids have been softened by cystic degeneration.
• Ovarian tumor: often cystic, unilateral and does not move with cervical displacement.
• Adenomyosis: more commonly causes uniform diffuse and tender uterine enlargement.

Management of Fibroid:

Therapeutic intervention depends on the woman’s desire for future pregnancy and the tumor size.

Medical management:

Hormone therapy may be used as a short-term intervention to decrease the size of fibroid and to minimize blood loss. Drugs used are antifibrinolytics, antiprogesterones, Danazol, GnRH analogous and prostaglandin synthetic inhibitors. Use of hormones for more than 6 months can increase the risk of osteoporosis.

●    If small and asymptomatic, conservative management with annual examination and ultrasound monitoring of size is sufficient. This is especially used in women over 40 because fibroids do not grow after menopause and may shrink.

●    Menstrual or pressure symptoms may dictate surgery.

●    Pain-requires analgesia.

●    Heavier and longer periods with anemia are the commonest indication for proceeding to surgery.

●    Embolization under radiological control: A cannula is passed into the uterine arteries via the femoral artery. The uterine arteries are embolized by injecting tiny silicon particles causing the fibroids to degenerate. Pain relief is essential for 48 hours. In women with large/multiple fibroids there is an increased risk of hysterectomy compared to surgical treatment. Pyrexia and abscess forination can occur. It is not recommended for women who wish to preserve their fertility, although live births have been reported following the procedure.

Surgical management :

1. 1. Abdominal hysterectomy:

Suitable when family is complete with women over the age of 40 or when the uterus is grossly enlarged and distorted by multiple fibroids.

1. 1. Vaginal hysterectomy:

When fibroids are small and few in number and there is an associated prolapse of the uterus.

1. 1. Myomectomy:

In young women whose families are incomplete or when there is a personal desire to retain the uterus. The procedure is often vascular and may cause scarring, with adhesion formation impairing fertility. If the fibroids are numerous it may be impossible to remove them all, and growth of the remainder may cause problems in the future. Women undergoing this procedure should be warned that the surgeon may have to proceed to a hysterectomy and consent to the possibility of this (1% risk).

Submucous fibroids may be resected with laser or diathermy through a hysteroscope.

Destructive Operations

Definition:

The destructive operations are designed to diminish the bulk of the fetus so as to facilitate easy delivery through the birth canal. In modern obstetric practice, virtually there is hardly any place for destructive operations. Neglected obstetrics requiring destructive operations are completely preventable. These procedures are difficult and may be dangerous too unless the operator is sufficiently skilled. Unfortunately, one may have to perform such operations while working in the unorganized sector. Some commonly performed operations are discussed here. There are four types of operations:

♦Craniotomy             ♦Evisceration             ♦Decapitation             ♦Cleidotomy

CRANIOTOMY

DEFINITION: It is an operation to make a perforation on the fetal head, to evacuate the contents followed by extraction of the fetus.

INDICATIONS: 

■ Cephalic presentation producing obstructed labor with dead fetus: This is the most common indication  of craniotomy in the referral hospitals of the developing countries.

■ Hydrocephalus even in a living fetus: This is applicable both for the forecoming and the aftercoming head .

■ Interlocking head of twins.

CONDITIONS TO BE FULFILLED: (1) The cervix must be fully dilated and (2) baby must be dead (hydrocephalus being excluded).

CONTRAINDICATION: (i) The operation should not be done when the pelvis is severely contracted so as to shorten the true conjugate to less than 7.5 cm (3″). In such condition, the baby cannot be delivered, as the bimastoid diameter (base of the skull) of 7.5 cm cannot be compressed. (ii) Rupture of the uterus where laparotomy is essential.

PROCEDURES: Preliminaries: The preliminary preparations are the same as mentioned in p. 642. The operation is to be done under general anesthesia.

Actual steps

Step I: The two fingers (index and middle) are introduced into the vagina and the finger tips are to be placed on proposed site of perforation. However, when the suture line cannot be defined because of big caput, the perforation should be done through the dependent part.

Sites of perforation: Vertex: On the parietal bone either side of the sagittal suture. Suture is avoided to prevent collapse of the bone thereby preventing escape of the brain matter. Face: Through the orbit or hard palate. Brow: Through the frontal bone.

Step II: The Oldham’s perforator  with the blades closed is introduced under the palmar aspect of the fingers protecting the anterior vaginal wall and the adjacent bladder  until the tip reaches the proposed site of perforation.

Step III: By rotating movements the skull is perforated. During this step, an assistant is asked to steady the head per abdomen in a manner of first pelvic grip. After the skull is perforated, the instrument is thrust up to the shoulders and the handles are approximated so as to allow separation of the sharp blades for about 2.5 cm. The blades are again apposed by separating the handles. The instrument is brought out keeping the tip of the blades still inside the cranium. The instrument is rotated at right angle and then again thrust in up to the shoulders. The handles are once more to be compressed so as to separate the blades for about 2.5 cm. The perforated area now looks like a cross. The instrument with the blades closed is then thrust in beyond the guard to churn the brain matter. The instrument, with the blades closed, is brought out under the guidance of the two fingers still placed inside the vagina.

 Alternative to Oldham’s perforator, similar procedure could be performed using a sharp-pointed Mayo’s scissors. 

Step IV: With the fingers brain matter is evacuated. The idea is to make the skull collapse as much as possible.

Step V: When the skull is found sufficiently compressed, the extraction of the fetus is achieved either by using a cranioclast or by two giant volsella. Giant volsella are used to hold the incised skull and scalp margins.

Step VI: The traction is now exerted in the same direction as like that mentioned in forceps operation. Step VII: After the delivery of the placenta, the uterovaginal canal must be explored as a routine for evidence of rupture uterus or any tear. Injection methergine 0.2 mg is to be given intravenously with the delivery of the anterior shoulder. The rest of the delivery is completed as in normal delivery.

Forceps versus craniotomy in a dead fetus: If the delivery of the uncompressed head can be accomplished without much force with consequent injuries to the mother, forceps delivery is preferred. But if it is found difficult and damaging to the mother, craniotomy is safer.

DECAPITATION

DEFINITION: It is a destructive operation whereby the fetal head is severed from the trunk and the delivery is completed with the extraction of the trunk and that of the decapitated head per vaginum. INDICATION:

(1) Neglected shoulder presentation with dead fetus where neck is easily accessible.

(2) Interlocking head of twins.

PROCEDURES: Preliminaries — The preliminaries to be followed are the same as outlined earlier. The operation is done under general anesthesia.

Actual Steps

Step I: If the fetal hand is not prolapsed, bring down a hand. A roller gauze is tied on the fetal wrist and an assistant is asked to give traction towards the side away from the fetal head to make the neck more accessible and fixed.

Step II: Two fingers of the left hand (middle and index) are introduced with the palmar surface downwards and the finger tips are to be placed on the superior surface of the neck—the proposed site of decapitation.

Step III: The decapitation hook with knife is to be introduced flushed under the guidance of the fingers placed into the vagina, the knob pointing towards the fetal head. The hook is pushed above the neck and rotated to 90° so as to place the knife firmly against the neck. The internal fingers, in the meantime, are placed on the under surface of the neck to guard the tip of the hook.

Step IV: By upward and downward movements of the hook with knife, the vertebral column is severed (evident by sudden loss of resistance). The rest of the soft tissue left behind may be severed by the same instrument or by embryotomy scissors. While removing the decapitation hook—it is to be pushed up; rotated to 90° and then to take out under the guidance of the internal fingers. The decapitated head is pushed up and the trunk is delivered by traction on the prolapsed arm.

Step V: Delivery of the decapitated head—Any of the following methods may be usually effective:

• By hooking the index finger into the mouth  • By holding the severed neck with giant vulsellum and delivery of the head as that of aftercoming head in breech  • Using forceps.

Step VI: Routine exploration of the uterovaginal canal to exclude rupture of the uterus or any other injury.

EVISCERATION

The operation consists of removal of thoracic and abdominal contents piecemeal through an opening on the thoracic or abdominal cavity at the most accessible site. The object is to diminish the bulk of the fetus which facilitates its extraction. If difficulty arises, the spine may have to be divided (spondylectomy) with embryotomy scissors.

The indications are: (1) Neglected shoulder presentation with dead fetus; the neck is not easily accessible and (2) fetal malformations, such as fetal ascites or hugely distended bladder or monsters.

CLEIDOTOMY

The operation consists of reduction in the bulk of the shoulder girdle by division of one or both the clavicles.The operation is done only in dead fetus (anencephaly excluded) with shoulder dystocia. The clavicles are divided by the embryotomy scissors or long straight scissors introduced under the guidance of left two fingers placed inside the vagina.

POSTOPERATIVE CARE FOLLOWING DESTRUCTIVE OPERATIONS

♦ Exploration of the uterovaginal canal must be done to exclude rupture of the uterus or lacerations on the vagina or any genital injury.

♦A selfretaining (Foley’s) catheter is put inside, especially following craniotomy for a period of 3–5 days or until the bladder tone is regained.

♦Dextrose saline drip is to be continued till dehydration is corrected. Blood transfusion may be given, if required.

♦Ceftriaxone 1 g IV infusion is given twice daily.

COMPLICATIONS: (1) Injury to the uterovaginal canal (2) rupture of uterus (3) postpartum hemorrhage—atonic or traumatic (4) shock—due to blood loss and/or dehydration (5) puerperal sepsis (6) subinvolution (7) injury to the adjacent viscera— bladder—vesicovaginal fistula or rarely to rectal wall leading to rectovaginal fistula and (8) prolonged ill health.