Generally,
the eligibility criteria of TAE for visceral artery aneurysms are as follows: 1) aneurysm whose diameter is more than 2 cm,
2) pregnant woman or patients who plan pregnancy,
3) aneurysm of growing tendencies and 4) pseudoaneurysm.
Pseudoaneurysms are common vascular abnormalities that represent a disruption in arterial wall continuity.
Some complications associated with pseudoaneurysms develop unpredictably and carry high morbidity and mortality rates [12].
Pseudoaneurysms may progress with development of complications such as infection,
development of local compression on neurovascular structures,
or rupture [13] or may undergo spontaneous thrombosis [14-15].
Prevalence of RAP after partial nephrectomy: literature review
Laparoscopic partial nephrectomy (LPN) is steadily gaining ground as an alternative procedure in place of the more conventional open partial nephrectomy (OPN) for T1a stage (0-4 cm) unilateral renal cell carcinomas (RCC) [3].
From literature review,
the incidence of the RAP after LPN is reported to be 2.0-4.0%,
which is predominantly higher than that after OPN,
0.4-0.6% [16,
17].
There have been many reports of case series about the frequency of the vascular complications after partial nephrectomy till now [6,
16,
17].
The interval from the surgery to the onset of post-operative haemorrhage is reported to be 6-222 days (mean,
14 days) [16,
17] although Ramani et al.
[6] reported four cases of postoperative haemorrhage among 200 cases of LPN,
which developed two days after the surgery
Delayed bleeding,
any haemorrhage that occurs after partial nephrectomy,
is reported to be related to the intraoperative warm ischaemia times (WITs): WIT in patients without delayed haemorrhage are reported to be significantly short compared with that in patients with delayed haemorrhage (14.2 minutes vs.
28.2 minutes) [17].
An additional difference between LPN and OPN is that OPN uses cold ischaemia while this is not done in LPN.
As a result,
a major disadvantage of LPN is in its increased warm ischaemia times (WITs).
These factors potentially contribute to increased perioperative times and overall complication rates [6-10].
In these days,
selective TAE becomes the first line treatment for the RAP after partial nephrectomy [16].
Present study: discussion with literature review
The prevalence of the RAP in this study was 51.3% (40 of 78 cases).
In the literature,
the frequency of the RAP was reported with 0.4-4.0%,
most of the cases were based on the data of angiography performed from 1 to 4 weeks later [16-17].
Therefore,
an asymptomatic RAP may be considerably detected in a high rate in the perioperative period if we use thin-slice 3D-CT.
Cohenpour M,
et al.
reported CT findings of RAPs after LPN of five patients [18]: three of the five patients whose diameter was 1.8 to 3.1 cm were diagnosed a postoperative RAP on contrast-enhanced CT.
The imaging findings of postoperative RAP were reported a well-circumscribed dense collection of contrast material located within the renal parenchyma on arterial phase.
The prevalence of extravasation in this study was 7.7% (6 of 78 cases).
The frequency of delayed postoperative haemorrhage was reported to be 1.2-7.5%: such extravasation was demonstrated on angiography and treated by TAE [17].
The mean postoperative days of disease onset was 11.7-20.5 days (range,
5-45).
In the present study,
the detection rate of extravasation was relatively high compared with the reports based on the angiographic findings: it is acceptable because CT can detect smaller foci of extravasation thanks to its high spatial resolution.
Most of the patients that an extravasation was detected in our study were asymptomatic.
The prevalence of the irregularity of renal arterial branch in this study was 57.7% (45 of 78 cases).
This frequency is obviously high; however,
there are few reports about the frequency of irregularity of renal arterial branch.
The mechanism of creation of the irregularity of renal arterial branch is unknown: it may be associated with the angiospasm,
ischemia or intraoperative clamp.
In a case with the RAP,
an irregularity of renal arterial branch was associated in 29 out of 38 patients (76.1%).
In contrast,
in the case without RAP,
an irregularity of renal arterial branch was associated in 25 out of 40 patients (62.5%).
In the first place,
these results correspond to each other because the irregularity of renal arterial branch and the RAP might be related to similar causes.
Natural history of RAPs after partial nephrectomy
In six cases (diameter,
2.0-5.3 mm) that were followed up,
60% regressed and 40% increased in 3D-CT 3-5 days later.
All the two patients underwent TAE and were successfully treated.
In 16 cases (diameter,
2.6-6.6 mm) that were followed up although there were RAPs but cannot be prospectively detected,
all the RAPs regressed in 5-mm thickness CT performed three weeks later.
Therefore,
we cannot find the relationship between the diameter and the outcomes of these RAPs smaller than 6.6 mm.
Difference in detection rates among reconstruction methods of perioperative 3D-CT
Detection rates among four reconstruction methods were good in the following order: 1 mm-axial,
MPR,
50 mm-MIP,
and 5 mm-axial.
The detection rates of the former two (1 mm-axial and MPR) were especially high.
The detection rate of the RAP by 5mm-axial image was lower: only 63% as compared with 1 mm-axial image.
To detect a RAP steadily,
the detailed interpretation from many directions using both 1mm-axial and MPR image is considered especially important.
Significance of perioperative 3D-CT after partial nephrectomy
The advantages of perioperative 3D-CT are as follows:
1.
It can detect promptly a RAP with the treatment indication during the perioperative period (screening of a RAP).
2.
It can detect a small RAP located in the complicated portion such as renal hilum or a RAP as compared with conventional 5 mm-axial CT image.
3.
The precise evaluation (diameter,
form or internal thrombosis of the RAP and hematoma around the kidney stump) on CT leads to decision of the treatment strategy (TAE or follow-up).
4.
It can detect an important associated finding (extravasation,
arterial venous fistula,
angiospasm or occlusion of renal artery).
Conclusion
In the early perioperative period in partial nephrectomy patients,
RAPs exist at high frequency as previously reported.
Many of the RAPs smaller than 6.6 mm spontaneously reduce its size or disappear during the perioperative period.
Treatment strategy about these RAPs should be discussed hereafter.
When the patients have no clinical manifestations,
such small RAPs should be treated only when they increased on follow-up 3D-CT.