Midline vs. Flank Laparotomy: The Right Surgical Approach for Uterine Torsion in Mares

Uterine torsion in mares is a surgical emergency where rapid decision-making directly affects both mare and foal survival. Once diagnosis is confirmed, the clinician must decide between two primary surgical approaches: standing flank laparotomy (SFL) or ventral midline laparotomy (MI). The choice should be based on case selection rather than surgeon preference alone ^1,2. 

Standing Flank Laparotomy (SFL) 

SFL is performed in the sedated standing mare under local anesthesia. Its biggest advantage is avoidance of general anesthesia, reducing anesthetic risk for both mare and fetus. Recovery is usually faster and safer, especially in heavily pregnant mares³. 

This technique is particularly useful: 

• Before 320 days of gestation 

• In calm, cooperative mares 

• When the fetus is alive and stable 

• When ultrasonography shows minimal CTUP enlargement and limited vascular compromise 

• In field conditions with limited surgical facilities 

Several studies suggest improved fetal survival with SFL in pregnancies below 320 days^1,3. 

However, SFL has limitations. Abdominal visualization is restricted, making assessment of uterine viability difficult. Manipulation can become physically demanding in large mares or advanced pregnancies. Surgeon size, strength, and experience significantly influence success. The approach is also risky in anxious or painful mares that may react during uterine handling. 

Ventral Midline Laparotomy (MI) 

MI is performed under general anesthesia through a ventral abdominal incision. The main advantage is superior abdominal access and visualization. The surgeon can thoroughly evaluate: 

• Uterine viability 

• Broad ligament vascular compromise 

• Concurrent gastrointestinal disease 

• Need for cesarean section²

This approach is generally preferred: 

• Beyond 320 days gestation 

• In agitated or unpredictable mares 

• When fetal death is confirmed 

• When severe CTUP enlargement or uterine edema is present 

• If uterine rupture risk is suspected 

• When concurrent gastrointestinal lesions cannot be ruled out 

Manipulation of the uterus is easier under general anesthesia, especially in severe torsions. Positioning adjustments such as tilting the mare or elevating hindlimbs can also assist correction. 

The major disadvantage of MI is anesthetic risk. Dorsal recumbency and hypotension may worsen uterine ischemia and compromise fetal perfusion³. Recovery is longer, postoperative care is more intensive, and costs are substantially higher. 

Practical Comparison of Surgical Approaches¹ 

Practical Surgical Decision-Making 

In practice, SFL works best in earlier gestation cases with a viable fetus, limited vascular compromise, and a cooperative mare. It is particularly valuable in ambulatory practice due to lower cost and field applicability. 

MI becomes the safer option in advanced pregnancies, severe torsions, compromised fetuses, suspected uterine damage, or when gastrointestinal involvement is possible. It also provides the best access if cesarean section becomes necessary. 

Ultimately, no single approach is ideal for every mare. The best outcomes depend on rapid diagnosis, accurate ultrasonographic assessment, appropriate case selection, and timely surgical intervention. 

Reference 

1. Samsel J, Gündemir O, Szara T, Witkowski M. Midline vs. flank laparotomy-criteria for choosing the optimal surgical technique for uterine torsion correction in the mare. BMC Veterinary Research. 2025 Sep 24;21(1):542. https://doi.org/10.1186/s12917-025-04883-w  

2. Khosa JS, Anand A, Sangwan V, Mahajan SK, Mohindroo J, Singh SS. Surgical management of uterine torsion through ventral celiotomy in eleven mares. Indian J Anim Res. 2020 Feb 1;54(2):244-8. https://arccjournals.com/journal/indian-journal-of-animal-research/B-3756  

3. Spoormakers TJ, Graat EA, Ter Braake F, Stout TA, Bergman HJ. Mare and foal survival and subsequent fertility of mares treated for uterine torsion. Equine Veterinary Journal. 2016 Mar;48(2):172-5. https://doi.org/10.1111/evj.12418