This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infeility (Eggs'plantation!), Subject name: Gynaecology & Obstetrics
A 26 year old infeile PCOS patient, treated with ovulation induction with clomiphene citrate, presents with sudden onset of abdominal pain and distension with ascites after 20 days of staing the tratment. what is the probable cause ? 
Select and explain. 
A. Uterine rupture, B. Ectopic pregnancy rupture, C. Multifetal pregnancy causing uterine distention, D. Ovarian Hyperstimulation syndrome
D: Ovarian Hyperstimulation syndrome
Answer: D: Ovarian Hyperstimulation syndrome 
Explanation: OHSS is a medical complication that is completely iatrogenic and unique to stimulatory infeility treatment. Its symptoms are the result of ovarian enlargement and fragility, extravascular fluid accumulation, and intravascular volume depletion Vascular endothelial growth factor , whose expression in granulosa cells and serum is augmented by hCG, and a variety of other inflammatory cytokines have been implicated in the pathogenesis of this disease This tends to be more severe with multiple gestation Clinical feature:- Abdominal distension, Abdominal pain, Nausea and vomiting. Management : Intravascular fluid intake to replenish the volume Symptomatic treatment , like tapping of the ascites and pleural effusion