This is a 13 year old female who presents to the 
E.D. with a one day history of increasing intermittent 
RLQ pain and the complaint of feeling "full".  She 
describes the pain as sharp and stabbing without 
radiation. Standing, running, and deep breathing make 
it worse.  There is no history of vomiting, diarrhea, or 
fever.  She denies urgency, frequency, or burning on 
urination.  She has had similar pain of less severity for 
the last two years, especially when running.  She has 
never had a menstrual period and denies being sexually 
active.
     She was born in Vietnam and moved to the U.S. two 
years ago.  Her PMH is negative.  Medications:  None.  
Immunizations are UTD.
     Exam:  VS T 38.8, P 118, R 24,  BP 108/69.  She is 
awake, alert, cooperative, and in no distress.  Oral 
mucosa moist.  Heart regular, no murmurs.  Lungs 
clear.  Abdomen non-distended.  There is mild to 
moderate tenderness in both lower quadrants and in the 
suprapubic area, but no rebound tenderness or 
guarding.  There are no palpable masses.  Bowel 
sounds are active.  Tanner Stage: Breasts IV, Pubic 
hair IV.  Color and perfusion are good.  Extremities 
unremarkable.

Laboratory studies:
CBC  WBC  15,500, 76% segs, 12% bands, 3% 
lymphs, 9% monos.  Hgb 12.8, Hct 39.1.  Platelet count 
265,000.  Chemistry panel normal.  Urinalysis normal.  
Urine HCG negative.
            

What is your diagnosis at this point?

An adolescent female presents with a long-standing 
history of intermittent abdominal pain that acutely 
worsens. She has well-developed secondary sex 
characteristics but has not reached menarche.  This 
makes an obstruction of the genital tract likely.  
Obstruction of the genital tract results in the 
accumulation of secretions, blood, or both within the 
uterus, vagina, or both, depending on the level of 
obstruction.  The three main types of congenital vaginal 
obstructions are:
   1.  Segmental atresia, usually midvagina.
   2.  Transverse vaginal septum, most common in the 
midportion.
   3.  Imperforate hymen.

View diagram of these types.

     The vagina proximally, and often the uterus are 
dilated, resulting in hydro(metro)colpos at birth or 
hemato(metro)colpos at puberty.  Examination of the 
genitalia in our patient reveals a thick, tense, bulging 
hymen at the introitus, which establishes the diagnosis 
of imperforate hymen.  On rectal exam a midline mass 
is palpable anteriorly.
     A pelvic ultrasound is performed.
 
View pelvic ultrasound.
     
     The sagittal view or long axis of the uterus (shown 
above) and transverse view (shown below) shows 
marked distention of the endometrial cavity, 
compressing the bladder anteriorly.  Scattered internal 
echoes represent blood, and mucous debris. The uterus 
is enlarged (14.9 cm by 8.3 cm by 6.3 cm).

View labeling on ultrasound.

     The uterine cavity is labeled as "U".  The bladder 
(labeled "B") is compressed.  The anterior abdominal 
wall musculature is labeled as "M".  The crosses mark 
the boundaries of the uterus.
  
     Contrast this with an ultrasound of the normal post 
pubertal uterus.

View normal pelvic ultrasound.

     The sagittal view is shown above.  The transverse 
view is shown below.  The maximum dimensions of the 
nulliparous uterus are approximately 8cm in length by 
5cm in width by 4cm in AP diameter.  The normal 
endometrial cavity is seen as a thin echogenic line as a 
result of reflection from the interface between the 
opposing surfaces of the endometrium.

View labeling on this normal ultrasound.

     The bladder (labeled "B") is dilated and fluid-filled in 
both views to optimize the transmission of ultrasound 
from the anterior pelvis.  The sagittal view (above) 
shows the myometrial wall labeled as "U".  The thin 
echogenic (white) line above the "U" represents the 
endometrial cavity with the opposing myometrium 
above this.  In the transverse view (below), the 
myometrium is labeled as "U".  The echogenic 
endometrial cavity is just above the letter "U" with the 
opposing myometrial wall above this.  The crosses 
mark the outer dimensions of the uterus in both views.
     Our patient is taken to the operating room.  A 
hymenectomy is performed, which allows the 
accumulated menstrual blood and vaginal secretions to 
drain.
     An imperforate hymen is a rare lesion, but it is the 
most common truly obstructive abnormality of the 
genital tract.  In one survey, it occurred in 0.1% of full 
term female neonates.  In imperforate hymen, the 
vagina is obliterated by a thick membrane interpreted 
as hymen, since no hymen remnants are identified.  
Some patients may present at birth with a large midline 
mass due to accumulation of vaginal secretions 
secondary to stimulation by maternal hormones.  The 
uterus and fallopian tubes may also be dilated 
(hydrometrocolpos).  In the presence of neonatal 
withdrawal bleed, a hematocolpos may develop, which 
presents as a dark purplish bulge at the introitus.  Most 
patients are asymptomatic at birth and during 
childhood, but present in late puberty with primary 
amenorrhea, cyclical crampy abdominal pain, and a 
pelvic mass due to accumulation of menstrual blood.  
An imperforate hymen is not of Mullerian origin; 
therefore it is not associated with other genitourinary 
abnormalities.  However, hematocolpos or hydrocolpos 
may lead to complete urethral obstruction or variable 
degrees of hydroureter or hydronephrosis as a result of 
the chronic extrinsic pressure.  Patients with 
imperforate hymen associated with hematocolpos also 
have an increased risk of endometriosis, which is felt to 
be secondary to the mechanical  obstruction and 
metaplasia.  If this retrograde flow is stopped early 
enough, endometriosis might be prevented.  Therefore, 
surgery should be scheduled promptly for adolescents, 
but can be delayed and performed electively for 
asymptomatic infants and children.
  
References:
     1.  Paradise JE.  Pediatric and Adolescent 
Gynecology.  In:  Fleisher GR, Ludwig S. Textbook of 
Pediatric Emergency Medicine, 3rd edition.  Baltimore, 
Williams and Wilkins, 1993, pp. 916-919.
     2.  Salem S. The Uterus and Adnexa. In:  Rumack 
CM,Wilson SR, Charboneau JW.  Diagnostic 
Ultrasound, Volume 1.  St. Louis, 1991, pp. 384-387.
     3. Currarino G, Wood B, Majd M.  The Genitourinary 
Tract and Retroperitoneum.  In:  Silverman FN, Kuhn 
JP.  Caffey's Pediatric X-Ray Diagnosis, Ninth edition, 
Volume 2.  St. Louis, 1993, pp. 1384-1388.
    4.  Sanfilippo J.  Endometriosis in association with 
uterine anomaly.  American Journal of Obstetrics and
Gynecology, 1986;154: 39-43.