The extrinsic pathway is activated by the tissue factor, which converts factor VII to VIIa which later on converts factors X and II to their activated form finally leading to the conversion of fibrinogen to fibrin fibres.

Twin gestations are at increased risk for postpartum haemorrhage (PPH). A number of maternal and peripartum factors are associated with PPH requiring blood transfusion in twin gestations. Reducing the rate of caesarean delivery in twin pregnancies may decrease maternal hemorrhagic morbidity.

This woman at her 37 weeks of gestation, has developed multiple herpetic lesions over her genitals. In every case were the mother develops herpes simplex infection after 28 weeks of pregnancy, chances for intrapartum and vertical transmission of the infection to the neonate is considered to be very high.

Risk factors of intrapartum herpes simplex infection of the child includes premature labour, premature rupture of membrane, primary herpes simplex infection and multiple lesion in the genital area.

The most appropriate methods for managing this case includes:
– checking for herpes simplex infection using PCR testing of a cervical swab.
– starting prophylactic antiviral therapy for the mother from 38 weeks of gestation until delivery.
– preferring a cesarean section delivery if there are active lesions present in the cervix and/or vulva.

Cesarean delivery is advised in this case along with maternal antiviral therapy before delivery to minimise the risk of vertical transmission.

Arcuate means ‘bow shaped’ and there are different arcuate lines in anatomical terms. Regarding the pelvic brim this is composed of the arcuate line of the ilium, pectineal line and prominences of sacrum and pubic symphysis (as demonstrated in the images below). As can be seen the arcuate line is a smooth rounded border on the internal surface of the ilium inferior to the iliac fossa and Iliacus. Image sourced from Wikipedia Note: The pelvic outlet is also called the inferior aperture. The pelvic brim is the superior aperture

The Uterine artery typically arises from the anterior branch of the internal iliac artery. It crosses the ureter ANTERIORLY. It is the primary source of arterial supply to the uterus and its branches anastomose with branches of the ovarian and vaginal arteries.

Tamoxifen is a SERM that is effective in treating hormone-responsive breast cancer, it acts as an antagonist to prevent receptor activation by endogenous oestrogen. As agonist of the endometrial receptors it promotes endometrial hyperplasia and hence increases the risk of endometrial cancer.

Around 30-40% of women affected by this condition complain of difficulty in conceiving.

The given case where the patient presents with sudden abdominal pain, cessation of uterine contraction and the urge to push along with vaginal bleeding is typical for uterine rupture. Examination shows a decreased or lost fetal heart rate, along with signs of fluid collection including fluid thrill and shifting dullness due to the entry of blood into the peritoneal cavity.
Other common manifestations of uterine rupture include:
– Loss of the station of the fetal presenting part
– Vaginal bleeding which is not be proportionate to the hemodynamic status
-Maternal tachycardia and hypotension ranging from subtle to severer shock
– Uterine tenderness
– Change in uterine shape and contour
– Easily palpable fetal parts
– No fetal presentation on vaginal examination
– Hematuria if the rupture extends to the bladder
Anterior lower transverse segment is the most common site of spontaneous uterine rupture.

Placenta previa usually presents as painless vaginal bleeding, which rules it out as the diagnosis in given case.

Vaginal bleeding with a tender and tense uterus is the presentation in placental abruption, also contrary to uterine rupture, uterine contractions will continue in case of placental abruption.

Cervical laceration can be a possibility, but in such cases more amount of vaginal blood loss was expected in this patient with hemodynamic instability. Also symptoms like deformed uterus, abdominal distention and cessation of contractions are inconsistent with cervical laceration.

Excessive generation of thrombin and fibrin in the circulating blood results in Disseminated intravascular coagulation (DIC) which leads to increased platelets aggregation and consumption of coagulation factors resulting in consequent bleeding at one site and thromboembolism at another. Placental abruption and retained products of conception in the uterine cavity are the most common obstetric causes of DIC. The condition will not fit as diagnosis in this clinical scenario.

Shoulder dystocia occurs when the bisacromial diameter, which is the breadth of the shoulders, exceed the diameter of pelvic inlet. This typically results in a bony impaction of the anterior shoulder against the maternal symphysis pubis, instead of an arrest at the pelvic inlet. Brachial plexus palsies including Erb’s palsy is the most common foetal injury associated with shoulder dystocia.

It is not hyper-extension but the hyper-flexion of maternal legs tightly on her abdomen, called as McRoberts manoeuvre, which facilitates delivery during shoulder dystocia. This technique is effective as it increases the mobility of sacroiliac joint during pregnancy, which allows the rotation of pelvis and thereby facilitating the release of fetal shoulder.
If this manoeuvre does not succeed, another technique called suprapubic pressure is done where an assistant applies pressure on the lower abdomen and gently pulls the delivered head. This technique is useful in about 42% of cases with shoulder dystocia.

Maternal diabetes mellitus and foetal macrosomia both are a risk factor for shoulder dystocia.

Administration of epidural anaesthesia during labour increases the possibility of shoulder dystocia.

Risk of shoulder dystocia may increase with Oxytocin augmentation also.

Majority of the lymph from the ovaries drain into the para-aortic lymph nodes.