External Os If there is a disorder in fusion of downgrowing Mullerian duct and upgrowing derivative of urogenital sinus. It results in Transverse vaginal septum which causes imperforate vagina (or vaginal agenesis). In a series repoed : - 46% septa were located in upper pa.deg Ott ti2v-a - 40% septa were located in middle pa.deg - 14% septa were located in lower pa.deg The upper pa corresponds to external os therefore it is the option of choice. Transverse vaginal septum can present either in : A. Neonatal age group ? The placental transfer of estrogen results in stimulatin the *lands of the endocervix which results in formation of Mucocolpos it can present as : abdominal tumour.deg can compress the ureter resulting in hydroureter followed by hydronephrosis.deg can compress the rectum resultina in obstioation / intestinal obstruction.deg B. At pubey ? Patient can present with Primary amenorrhea (actually called as Cryptomenorrheaa as uterus menstruates normally but blood does not come out due to outflow Tract obstruction).deg Secondary sexual characteristics are normal.deg Due to Cryptomenorrhoea, blood gradually collects and distends first the vagina (hematocolpos)deg then cervix uterus (hematocervix and hematometra) and finally the tube (hematosaipinx)deg. All these present as pelvic/ abdominal tumour. The abdominal tumour can irritate the bladder followed by compression of internal urinary meatus leading to complete retention of urine (This occurs 3 - 4 years after the onset of hidden menstruation and therefore patient is generally aged 15 - 18 yearsdeg). Patient may complain of monthly cyclic pain (backache I lower abdomen pain).deg Management ? Once the diagnosis of cryptomenorrhea is made, surgical treatment is urgently requireddeg since every menstrual episode fuher dilates the genital tract and threatens permanent impairment of reproductive function. Obstruction at the level of the cervix is managed by uterovaginoplasty. If uterovaginoplasty is unsuccessful hysterectomy is performed. When the outflow menstrual blood is prevented by a thick vaginal membrane at any level, incision followed by covering the deficiency with either vaginal epithelium or skin grafting is done. When the obstructing membrane is thin and low down, the membrane is merely excised.deg