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Subinvolution of Placental Sites 951

VetBooks.ir Diseases and Disorders

SUBINVOLUTION OF PLACENTAL SITES A vestibular smear from a dog with subinvolution of placental sites
(SIPS). A trophoblast cell is visible as a polynucleated, vacuolated giant cell. (Courtesy Auke C. Schaefers-Okkens.)

and a mild serosanguineous discharge may • Abdominal ultrasonography: focal thicken-
last 3-5 weeks postpartum. ings of the uterine wall and a fluid-distended
• With SIPS, placental cells (trophoblasts) lumen; color Doppler velocity measurements
continue to invade the endometrium and of blood flow differentiates SIPS from SUBINVOLUTION OF PLACENTAL SITES Enlarged
uterine segments were visible at the time of ovar-
myometrium after the placentas have been normally involuting uteruses. iohysterectomy in a bitch with severe metrorrhagia.
delivered. • Abdominal radiographs: focal areas of uterine They may be palpable per abdomen. (Courtesy Auke
• Failure of these cells to regress prevents irregularity C. Schaefers-Okkens.)
normal uterine involution, resulting in
chronic hemorrhagic vulvar discharge. TREATMENT
DIAGNOSIS Treatment Overview ○ Affected bitches are not predisposed to
• Often, spontaneous remission occurs without SIPS in subsequent pregnancies.
Diagnostic Overview the need for medical or surgical intervention. ○ Rarely, trophoblastic cells cause uterine
• The diagnosis is based on hemorrhagic • Hysterectomy and possibly curettage is neces- perforation and subsequent peritonitis.
vulvar discharge that ranges in severity from sary in acute cases with severe metrorrhagia. • Poor: if acute exsanguination (rare); uterine
self-limited and not producing overt signs perforation and peritonitis (rare)
to life-threatening metrorrhagia requiring Acute General Treatment
transfusion. • Observation (benign neglect) PEARLS & CONSIDERATIONS
• The diagnosis is often presumptive, unless ○ Erosion through the uterine wall resulting
accompanied by uterine histopathology. in peritonitis is possible but rare. Comments
○ In most cases, SIPS resolves spontaneously. SIPS is the most common cause for persistent
Differential Diagnosis • Curettage may be attempted if bitch is postparturient serosanguineous vulvar discharge
• Exogenous estrogens intended for future breeding and/or hemor- in an otherwise healthy bitch.
• Metritis rhage is severe.
• Vaginitis • Hysterectomy is indicated if the bitch is not Prevention
• Vulvar, vaginal, or uterine tumor intended for future breeding and hemorrhage Hysterectomy or not breeding an intact female
• Urinary tract hemorrhage (e.g., bacterial is severe. dog prevents this problem from occurring.
cystitis, calculi) • Acute life-threatening uterine bleeding may
• Coagulopathies require blood transfusion (p. 1169). Technician Tips
• Brucellosis • Systemic and intrauterine antibiotics may Advise client to monitor the color of mucous
• Trauma be indicated when metritis or peritonitis is membranes for signs of anemia.
present.
Initial Database Client Education
• CBC, serum biochemistry profile, urinalysis: Recommended Monitoring Careful monitoring for complications such
unremarkable. NOTE: mild normocytic, nor- Serial weekly/biweekly clinical, hematologic, as systemic illness and metritis (foul-smelling
mochromic anemia is normal in postpartum and ultrasonographic exams. Recheck animals discharge)
bitches. showing any signs of systemic illness, and look
• Vaginal cytologic exam: a typical finding is for complications (e.g., anemia, rarely uterine SUGGESTED READING
trophoblasts. perforation and peritonitis). Dickie MB, et al: Diagnosis and therapy of the
subinvolution of placental sites in the bitch. J
Advanced or Confirmatory Testing PROGNOSIS & OUTCOME Reprod Fertil Suppl 47:471, 1993.
• Definitive diagnosis: histologic exam based
on biopsy specimen of placental sites (rarely • Good: many females recover without AUTHOR: Carlos M. Gradil, DVM, MS, PhD, DACT
EDITOR: Michelle A. Kutzler, DVM, PhD, DACT
done) treatment.
• Vaginoscopy (p. 1184): to distinguish vaginal ○ With spontaneous remission, future
bleeding from blood derived from the uterus reproductive success is not compromised.

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