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Effect of ventral versus flank approach in caesareans on ewe mortality 

Clinical Scenario

You arrive at Mrs Jones’ to lamb one of her prize sheep, which turns out to have a big single lamb which is in breech presentation. With trepidation you tell her that the ewe needs a caesarean. The last C-section you did on one of her ewes, which you did left flank, went very well but the ewe ended up with a retroflexed bladder and was euthanased. Mrs Jones has never forgotten this and she is telling you that the nice New Zealand locum who caesared her last ewe did a ventral approach and the ewe was fine on that occasion. She wants to know which approach you are going to use. You wonder if there is any evidence to suggest whether surgical approach affects survival...

3-Part Question (PICO)

In [sheep undergoing caesarean section] [does a ventral approach compared to a left flank approach] [reduce mortality in the ewe]?

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

sheep.mp. OR ovine.mp. OR ovines.mp. OR ewe.mp. OR ewes.mp. OR exp Sheep/

AND

Caesar$.mp. OR Cesar$.mp. OR c section.mp. OR exp Cesarean Section/

AND

ventral.mp. OR midline.mp. OR lateral.mp. OR flank.mp. OR laparotomy.mp. OR linea alba.mp.

CAB Abstracts 1910 to Present using the OVID interface

sheep.mp. OR ovine.mp. OR ovines.mp. OR ewe.mp. OR ewes.mp. OR exp sheep/

AND

Caesar$.mp. OR Cesar$.mp. OR c section.mp. OR exp caesarean section/

AND

ventral.mp. OR midline.mp. OR lateral.mp. OR flank.mp.OR laparotomy.mp. OR linea alba.mp. OR exp laparotomy/

Search Outcome

MEDLINE

  • 20 papers found in MEDLINE search
  • 19 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from MEDLINE

CAB Abstracts

  • 21 papers found in CAB search
  • 19 papers excluded as they don't meet the PICO question
  • 1 papers excluded as they are in a foreign language
  • 0 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from CAB

Total relevant papers

1 relevant papers from both MEDLINE and CAB Abstracts

Summary of Evidence

Ennen et al. (2013) Germany

Title:

Puerperal development of ewes following dystocia: a retrospective analysis of two approaches to caesarean section

Patient group:

192 ewes (1-16yrs of age) presented to a referral hospital; of these

119 ewes underwent caesarean section

Study Type:

Retrospective cohort study (using clinical records)

Outcomes:
  • Haematology: packed cell volume, erythrocyte number, haemoglobin, white blood cell count
  • Biochemistry: pH, base excess, bicarbonate, glucose, lactate, sodium, potassium, chloride, ionised calcium
  • Clinical examination
  • Assesment scale for the healing of surgical site
  • Foetal death
  • Development of complications
  • Hospitalisation period

Key Results:
  • No significant difference between left flank (16/86) and ventral (3/33) surgical approach on ewe mortality (no p value given)
  • No significant difference between surgical approaches in terms of live/dead lambs (p = 0.53)
  • No significant differences between surgical approaches for retained foetal membranes (RFMs) in either group (p = 0.73); 50 animals had RFMs in left flank group (69.4%) and 19 animals had RFMs in ventral group (73.1%)
  • Healing disorders were recorded in 23/119 (19.3%) ewes - 17 in the left flank laparotomy group and 6 in the ventral group.
  • There were significantly more major healing disorders (defined as dehiscence, high degree of pain, high degree of discharge and/abscess formation) in the left flank approach (p=0.04).
  • The median hospitalisation period was 13 days (16.0 +/- 7.6 days) for the left flank group and 12 (12.0 +/- 6.0 days) days for the ventral group (no p value given)

Study Weaknesses:
  • No sample size calculation
  • Small number of cases
  • Large difference in numbers between the treatment groups
  • Comparisons were frequently made across three groups (flank, ventral and non surgical correction). Only 119 ewes had a caesarean, so it is sometimes difficult to determine statistical significance between flank and ventral approaches
  • Treatment option decided by clinicians on a case by case basis, which could lead to biases as to the reason why the method was chosen
  • The ewes had been in labour for up to 3 days (median 0.5 days) and the treatments were carried out on referred cases which could bias the level of severity of the cases presented with dystocia
  • Healing of surgical site scale is not a validated method
  • Results contain information not associated with the aims of the study
  • The non–significant results are not discussed as readily as the significant ones in the discussion
  • There are no details about ethical approval of the study
Attachment:
No attachments.

Comments

This was a retrospective cohort study so more open to bias than a prospective cohort study or randomised control trial. A cohort study is not as good as a randomised controlled trial for comparing to treatment interventions, 

Bottom line

There is no difference in mortality between the two surgical approaches based on the limited evidence available.

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

Ennen S, Scholz M, Voigt K, Failing K, Wehrend A, (2013). Puerperal development of ewes following dystocia: a retrospective analysis of two approaches to caesarean section. Veterinary Record 172: 554.

About this BET

First author:
Martin Downes
Second author:
Rachel Dean
Institution:

CEVM, The University of Nottingham

Search last performed:
2016-12-14 17:22:58
Original publication date:
2014-11-14 17:22:58
Last updated:
2016-12-14 17:22:58
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