EP475 - Establishment and Evaluation of an Animal Model of Obstetric Traumatic Anal Incontinence

ePoster Presenter(s)

• 

  YAN PAN, Master's degree

  Graduate Student
  Longhua Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
  Shanghai University of Traditional Chinese Medicine
  SHANGHAI, Shanghai, China (People's Republic)

  Disclosure information not submitted.

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Author(s)

• QD

  QINGJUN DONG, Chief physician

  Deputy Director of the Department
  Anorectal surgery department, Longhua hospital of shanghai university of TCM
  shanghai, Shanghai, China (People's Republic)

  Disclosure information not submitted.
• 

  TONG SU, 在读状态 (she/her/hers)

  graduate student
  上海中医药大学附属龙华医院
  上海中医药大学附属龙华医院
  上海市, Shanghai, China (People's Republic)

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose
• 

  ZHIYONG MAO

  Resident
  Longhua Hospital Affiliated to Shanghai University of Traditional Chinese Medicine
  shanghai, Shanghai, China (People's Republic)

  Disclosure information not submitted.
• JH

  JINCHAO HE, Master's degree

  Graduate Student
  Longhua Hospital Affiliated with Shanghai University of Traditional Chinese Medicine
  Shanghai, Shanghai, China (People's Republic)

  Disclosure information not submitted.
• QQ

  QIN QIN, Associate researcher

  Associate researcher
  Institute of Chinese Traditional Surgery, Longhua Hospital, Shanghai University of Traditional Chinese Medicine,
  Shanghai, Shanghai, China (People's Republic)

  Disclosure information not submitted.

Purpose/Background: Backgroud: Obstetric traumatic anal incontinence is a functional disorder caused by damage to the pelvic floor sphincter muscles and pudendal nerves during vaginal delivery, representing the primary type of anal incontinence in women.

Currently, there remains a lack of mature and stable animal models for obstetric traumatic anal incontinence. Some previously reported modeling approaches exhibit limited observation periods, restricted evaluation metrics, and a deficiency in multidimensional physiological assessment indicators.

Purpose:A model of obstetric traumatic anal incontinence was established using Wistar virgin rats, with model efficacy validated through multidimensional physiological indicators.

Methods/Interventions:

Method: After 7 days of acclimatization feeding in the animal facility, rats were randomly divided into a control group (n=6) and a model group (n=18). A rat model of obstetric traumatic anal incontinence was established using a balloon compression intervention on the pelvic floor. At three postoperative time points (Day 7, Day 14, Day 21), The efficacy and duration of the disease model were evaluated by measuring fecal water content, rectal water retention time, maximum anorectal contraction pressure, electromyography (EMG), HE staining of the external anal sphincter, and Masson's trichrome staining.

Results/Outcomes:

Results: The rat model of obstetric traumatic anal incontinence established in this study exhibited pathological alterations including increased fecal water content, decreased maximum anorectal contraction pressure and rectal water retention time, neurogenic damage demonstrated by electromyography, and heightened skeletal muscle fibrosis.

Conclusion/Discussion:

Conclusion: This model effectively replicates the phenotypic characteristics of obstetric traumatic anal incontinence. By employing multiple physiological assessment methods, it demonstrates sustained stability in model performance, providing a valuable platform for subsequent research into the pathogenesis and intervention therapies for obstetric traumatic anal incontinence.

The details of molding process
The figure illustrates the process of pelvic floor modeling via balloon compression. After anesthetizing the rat, secure its limbs with rubber bands on the fixation table, fully expose the abdomen, and disinfect the area with alcohol spray. Make a 2cm longitudinal incision along the midline of the lower abdomen, sequentially dissecting through skin, fascia, and muscle layers. Retract the cecum and omentum laterally to optimize visualization of the uterus, locating the dorsal aspect of the cervix. Using a size 6 pediatric catheter, thoroughly lubricate the catheter tip with paraffin oil. Insert the catheter through the vaginal opening until it reaches the uterovaginal junction. Make a small incision (approximately 2 mm long) at the uterovaginal junction and withdraw the catheter through this incision. Inject 3 ml of saline solution into the balloon from the tail end toward the head end of the catheter. Attach a spring balance to the tail end of the catheter, suspend a 200g weight from the tail end of the balance, and allow it to fall vertically. Monitor the spring balance reading to ensure the weight remains consistently at 200g. One hour after molding, completely withdraw the saline solution from the balloon via the catheter's tail end. Then, cut and remove the catheter from the upper uterine segment to prevent further damage to the vaginal opening. Inspect for visceral bleeding. Use 4-0 absorbable suture (round needle) to sequentially suture the muscle, fascia, and skin layers.
Results of the model
Figures A-C show fecal water content, rectal water retention time, and maximum anorectal contraction pressure for each rat group, respectively. (**** P < 0.0001 vs. D7 MODEL group; NULLNULL P < 0.0001 vs. D14 MODEL group; $$$$ P < 0.0001 vs. D21 MODEL group. N=6 per group).

Figures D (1) to (4) display representative images of abnormal electromyographic findings in the model groups (measured using concentric needle electrodes on the external anal sphincter on day 21 post-surgery), showing increased percentage of continuous multiphasic waves, elevated MUAP amplitude during movement, and the appearance of positive sharp waves and fibrillation potentials during rest. Figure D(5) shows recruitment interference phases during maximal contraction in the sham-operated group.

Figure E presents a three-line table summarizing the number of polyphasic waves recorded within 10 minutes and MUAP amplitude across groups (compared to the sham-operated group, *** indicates P < 0.001, **** indicates P < 0.0001. N = 6 per group).

Figure F presents representative histological images of the external anal sphincter muscle from rats in each group, stained with HE and Masson's trichrome, at different magnifications.