There is a specific moment somewhere between 6 and 18 hours post-operatively when a failing anastomosis can still be saved. After 24 hours, your odds drop to nearly zero. This is the salvage window. Everything in your post-operative setup should be built around protecting it.
The data on this are unambiguous, drawn from 44,031 free flaps analysed in Shen et al.'s 2021 systematic review in the Journal of Reconstructive Microsurgery. The numbers are so stark that they should reframe how every new DIEP programme thinks about post-operative investment.
|
93.8%
Salvage within 24 hours
|
83.3%
Salvage on Day 2
|
12.1%
Salvage on Day 3
|
0%
Salvage after Day 4
|
Source: Shen et al., Journal of Reconstructive Microsurgery 2021 — systematic review of 44,031 free flaps
The Q1h protocol is not optional
Cervenka's 2017 multi-institutional study of 1,085 patients found that nurse-led hourly monitoring is the single most significant determinant of flap salvage — more impactful than the monitoring technology used, more impactful than resident check frequency.
The practical monitoring ladder for the post-operative period:
| Time window | Check frequency | Method |
| 0–24 hours | Every 1 HOUR | Clinical assessment + handheld Doppler |
| 24–48 hours | Every 2 HOURS | Clinical assessment + Doppler |
| 48–72 hours | Every 4 HOURS | Clinical checks |
| Day 3–7 | Every 6 HOURS | Nurse-led assessment |
Recognising compromise: what to look for
Venous compromise (59.5% of all failures)
Flap becomes congested, purple, engorged. Capillary refill initially normal then rapid. Doppler signal present but muffled or monophasic. Temperature drop relative to adjacent skin.
Arterial compromise (27.9% of all failures)
Flap becomes pale and cool. No capillary refill. Doppler signal absent. Requires urgent return to theatre — arterial salvage rates are significantly lower than venous.
Haematoma (10.2% of all failures)
Sudden swelling and firmness. Pain in an awake patient. Skin colour changes are secondary. Evacuation and vessel inspection required urgently — haematoma causes secondary anastomotic failure through compression.
Monitoring technology options by budget
| Modality | Sensitivity | Specificity | India Cost |
| Clinical (q1h trained nurse + Doppler) | ~82% | ~90% | ₹0 (training only) |
| FLIR ONE Pro (smartphone thermography) | ~90% | ~95% | ₹30K one-time |
| Implantable Cook-Swartz Doppler | 78% | 88% | ₹15K per case |
| NIRS (ViOptix / continuous) | 99.4% | 99.4% | ₹8–15L capital |
⚠️ Non-negotiable before your first DIEP case
If you cannot guarantee 24/7 OR take-back within 6 hours of recognised compromise, you should not perform DIEP until this system is in place. Monitoring without take-back capacity is worse than no monitoring: it creates the illusion of safety without the ability to act on it.
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View All Instruments →Sources: Shen et al. JRM 2021 (n=44,031); Cervenka et al. 2017 (n=1,085); Henriksson 2021 (n=547); PMC6846307 NIRS meta-analysis.